Procedures

This chapter is a guided tour through the most common ways of using CADRaster. In order to provide you with some drawings to play with, Setup has installed a number of sample documents in the DOC subdirectory. But first let’s have a closer look at the two cornerstones of CADRaster: hybrid raster-vector editing and Tessel Composite Documents.

CADRaster’s composite document viewer supports a number of raster formats (see the section called “Appendices”) including full-color pictures, e.g. photographs. Similarly to monochrome scanned images, color pictures may be equally well assigned the scale and other parameters that define the image position in the AutoCAD’s world coordinate system.

Start CADRaster and click the Open button on the toolbar. For File Type choose TIFF and open the photo.tif file from the DOC subdirectory. Click the Control doc button and inspect the parameters in the Raster Image Properties dialog, as in the figure below.

The Effective Image Extents of the photograph on the AutoCAD screen result from the Scale (1:300), Resolution (300x300 dpi), Units (mm) and the Insertion Point (0.0,0.0 mm). Please try to change those parameters in the Raster Image Properties dialog, close it and, after the regeneration ends, check how they affect the extents of the image on the graphics screen.

The background color image can be moved, i.e. its origin changed, interactively on the graphics screen. Click the Move button on the CADRaster toolbar. Click at a point on the image for which you want to define new coordinates (Base raster point), and then click where that point should be moved to on the screen (Destination point). The image regenerates at the new position. To move it back, click the Undo button on the CADRaster toolbar.

You may enter the coordinates numerically. Click the Move button again. Instead of showing the base raster and destination points with the cursor, type:

2500,6700 Enter

0,0 Enter

Once the extents and the origin of the image have been established properly, you may, of course, use all AutoCAD drafting commands to create DWG drawings on the color photograph background. Whenever you need, e.g. for the reasons of the graphics screen clarity, to take the color picture temporarily off the screen, simply click the Off button on the CADRaster toolbar. The button changes to On, so that you can bring the background image back, when you need it there.

Comparing raster images

CADRaster’s capability of handling composite documents is useful while comparing different versions made of the same raster image.

If you have any DWG open, click the AutoCAD’s New button to close it. Click the Open button on the CADRaster toolbar or ribbon, for File Type choose Tessel Composite Doc (TCD), and open the electric.tcd document from the DOC subdirectory. The document should appear on the AutoCAD screen as a scanned electrical drawing in blue, with a few red lines. The status line of the CADRaster toolbar should read ELECTRIC.TCD (electric.tif, electnew.tif) showing that there are two sub documents in the composite document. In order to find more detailed information, click the Document Properties on CADRaster ribbon or Control doc button on the CADRaster toolbar and when the Composite Document dialog pops up, click at the second entry on the Subdocuments list, so that electnew.tif is highlighted. Click the Properties... button to see that image parameters. Click the Color tab to see the page that defines the presentation color for this monochrome raster image (1-red), as shown in the figure below. Click Cancel to close the Raster Image Properties dialog.

While having electnew.tif highlighted, click the Bring forward button on the right side of the Subdocuments list, so that this drawing’s entry moves to the top of the list. Click the Select button in order to prepare electnew.tif for editing. Click the Close button to leave the Composite Document dialog and to regenerate the view of the composite document according to the new order of subdocuments. The color of the image on the screen will turn red, as the red electnew.tif is now covering most of the blue electric.tif, except of the small part that has been deleted from electnew.tif and remains visible in blue.

Click the Clear button on the CADRaster toolbar or ribbon (if the command line mentions Polygon, use OTM and switch to Rectangle, check if the Opaque mode is selected) and choose a rectangular area of the red image to be cleared. Accept the clearing operation and watch as another part of the blue image underneath gets uncovered. Close AutoCAD and CADRaster without saving the changes made to the ELECTRIC.TCD document, which also cancels all changes made to the sub documents.

Creating composite documents

As we have shown in the previous section, CADRaster can operate on composite documents that consist of a number of sub documents. A composite document itself may be seen as a list of links (path names) to files that contain raster or, optionally, vector drawings.

In order to create a sample composite document, start CADRaster and click the Document Properties button on its ribbon or Controll doc toolbar. The Composite Document dialog that pops up shows the empty Subdocuments list and all command buttons grayed, except Add. Click the Add button, choose the CADRaster’s DOC subdirectory and the File Type TIFF in the Add Document File(s) dialog; select four (4) files townmap1.tif ... townmap4.tif and click the Open (OK) button. The selected files will be added to the Subdocuments list, as shown in the figure below. The image will be regenerated after you close the Composite Document dialog and click the Zoom whole doc button on the CADRaster toolbar.

The composite document inherits its Units from the first added subdocument’s TAF attribute file (townmap1.taf), and its Common Extents represent the combined area of all subdocuments.

Click the Save button on the CADRaster ribbon or toolbar and save the UNNAMEDx composite document as map.tcd, so that the existing townmap.tcd is not overwritten.

Selecting and controlling subdocuments

In the preceding sections we were modifying single raster images that were selected for editing operations automatically, as the Auto select single file documents configuration option has been checked. Whenever CADRaster operates on a multi-file composite document, the sub documents to be affected by the editing operations must be selected by the user.

Click the Open button on the CADRaster ribbon or toolbar, for File Type choose Tessel Composite Doc (TCD), and open the townmap.tcd document from the DOC subdirectory. Note that CADRaster’s editing buttons, like Clear, Move, etc., are disabled (grayed). The CADRaster toolbar’s status line should show TOWNMAP.TCD (townmap4.tif, townmap3.tif, ...), as to identify the opened document and the nothing selected for editing status.

Click the Select Document on ribbon or Selecting on toolbar button and, after the subdocuments’ extents are shown and the toolbar changes to the RSELECT status dialog, hold down the Shift key and click the left mouse button at the upper left and then at the lower right segment of the map on the screen. The selected segments (subdocuments) will be marked by the rectangles of their viewports drawn with rectangular tracker marks at their corners and midpoints, as shown in the figure above.

Click the right mouse button to finish the selection process. The CADRaster toolbar’s status line should now read Selected: 2 of 4, and the editing buttons should now be enabled.

If you want to check the selection status on the Subdocuments list, or it is more convenient to do the selection there, click the Document Properties on CADRaster ribbon or Control doc button on the CADRaster toolbar. The Composite Document dialog will show the two selected entries of the Subdocuments list, townmap4.tif and townmap1.tif, preceded by the S selection mark and displayed in red, as shown in the next figure.

You may combine the both methods of selecting: graphical - using the Select Document\Selecting button and clicking at the images on the screen, and from the Subdocuments list - using the Document Properties or Control doc button, highlighting the drawings on the list and clicking the Select and Unselect buttons in the Composite Document dialog.

Close the Composite Document dialog, click the Clear button on the CADRaster ribbon or toolbar. Define a large rectangle around the center of the map, so that it includes portions of all four (4) segments of the map. Accept the clearing operation. After the image regenerates, you should see that the editing operation has affected only the two (2) selected images, leaving the others unchanged.

Click the Undo button on the CADRaster ribbon or toolbar. The last editing step will be cancelled for both selected images. Click the Selecting button again, and click Esc (or the right mouse button without selecting anything this time). CADRaster will return to the nothing selected state, the toolbar’s status line will show the document name, and the editing buttons will get disabled (grayed).

Merging subdocuments into single raster files

Keeping subdocuments in separate image files and having them logically connected in a single TCD document is a recommended way of working and should be used whenever possible. Sometimes however, a need may arise to merge selected subdocuments into a single raster file, e.g. in order to make the combined images available to applications that do not support composite documents.

Open TOWNMAP.TCD and select two subdocuments, as described in the previous section on Selecting and controlling subdocuments. Type RMerge command on the keyboard and type a new file name for the merged file in the Merge file dialog box that pops up on the screen, e.g. maps1&4.tif. After having the merge operation completed, open the newly created file. It should contain the selected subdocuments merged into one file, as shown below.

The RMerge command is particularly useful when merging a larger number of subdocuments selected from a complex TCD file with dozens or even hundreds of subdocument links. It is worth appreciating that each subdocument preserves its position in the world coordinates system, so, if the source subdocuments were calibrated, the merged result will be equally well calibrated without any additional actions.

DWG drawings in foreground and in background

In CADRaster sessions AutoCAD drawings (DWG) may appear in the foreground, when opened by AutoCAD for editing and optionally, in the background, when viewed by CADRaster either as single drawings or as subdocuments of a composite document.

Start CADRaster, click the AutoCAD’s Open button and choose the parcels.dwg drawing from the DOC subdirectory. The DWG drawing shows two (2) hatched polygons and a text informing that its background map is a composite document townmap.tcd. Click the Open button on the CADRaster ribbon or toolbar, for File Type choose Tessel Composite Doc (TCD), and open the townmap.tcd document from the DOC subdirectory.

Click the Document Properties on ribbon or Control doc button in order to see the Subdocuments list. At this time the session consist of the parcels.dwg, that is opened by AutoCAD and shown in its title bar, and TOWNMAP.TCD (townmap4.tif, ..., townmap1.tif), that is opened by CADRaster and shown in its status line and in the Composite Document dialog.

In order to create a single document that contains references to all background images and to the foreground DWG drawing, we are going to include a reference to the current DWG drawing in the composite document.

Close the Composite Document dialog. Click the Add DWG to TCD button on CADRaster ribbon or Add foreground to document button on a toolbar and click the Document Properties or Control doc button to open the Composite Document dialog again.

At this time you should see a reference to the DWG file added to the list of subdocuments. The F flag denoting that this is a foreground drawing should precede its pathname. Close the dialog. Click the Save as button on the CADRaster ribbon or toolbar and save the modified composite document as estate.tcd.

Close the CADRaster session and start the program again. Click the Open button on the CADRaster toolbar and open the newly created estate.tcd.

Note that parcels.dwg is automatically opened for foreground editing by AutoCAD. The background is provided by the remaining subdocuments of estate.tcd, i.e. townmap4.tif, ..., townmap1.tif.

Using Magnifying Glass

CADRaster’s Magnifying Glass tool provides quick and transparent access to a detailed view of the raster background in the neighborhood of the current cursor position. Magnifying Glass is an important support tool for snap to raster functions, as described in the next section of this manual, and for this reason it is controlled by the same dialog. It is, however, very useful also independently from snapping and may be used for quick viewing of image details and precise manual positioning of the cursor on the raster background while executing AutoCAD and CADRaster commands.

Start CADRaster and open office.tif. Click the Configuration button and choose the Magnifying Glass tab. Check the Magnifying Glass active and Pop up on hot key pressed options - this will let you pop up Magnifying Glass by clicking Shift. Default values for Size (100 pixels) and Magnification (3 times) should do fine for most images, but you may, of course, change them as needed. If you are using Shift+RightClick for AutoCAD pop up menu, it may be wise to change the Magnifying glass hot key to something else, say F12.

Use AutoCAD’s Line command to draw an outline of the scanned floor drawing, or to connect any specific points of it. This practically forces you to use AutoCAD’s ZOOM/Window and CADRaster’s Zoom whole doc commands repeatedly, which is certainly not convenient.

Now repeat the same exercise using Magnifying Glass. Click the CADRaster’s Zoom whole doc button to show the entire document. Start AutoCAD’s Line command and place the cursor at the intended beginning of the line on the raster background. Click the Shift key (Magnifying Glass hot key). The Magnifying Glass pops up showing an enlarged neighborhood of the cursor position, an image of the AutoCAD’s cursor at the moment of pressing Shift, and a small cross cursor that you may use to define a point within the Magnifying Glass window.

Place the cross cursor precisely on the enlarged raster background and click left mouse button to define a point. The AutoCAD’s Line command receives the point’s coordinates, the Magnifying Glass window disappears, and you may proceed to define next point. Please notice that you may close the Magnifying Glass window without defining a point simply by moving the mouse cursor outside of it.

Magnifying Glass is equally usable while defining those CADRaster commands that require precise graphical input. ZOOM/Window to show the lower half of the office.tif image. Click the Clear button on CADRaster toolbar. Try to clear interiors of rooms located next to the stairs. It is much easier to define rectangle or polygon corners when you click Shift and define each point through Magnifying Glass.

When you need to have a better control over the exact position of points that are being entered through Magnifying Glass, check the Keep on display option on the Magnifying Glass tab of the CADRaster Configuration dialog. This will make the Magnifying Glass pop up window wait on the screen until you click the right button to accept the entered point position. Press Esc to close Magnifying Glass without defining a point.

Using raster snap

Drafting on the background of scanned images can be made more convenient and productive with help of CADRaster’s selective Raster snap function. Snapping to raster features may be enabled permanently or transparently called from within AutoCAD or CADRaster commands.

Note

Please remember that in 64-bit version of CADRaster, raster snaps have been replaced by intelligent snaps so snap options are set automatically.

Start CADRaster and open office.tif. Click the Configuration button on CADRaster ribbon or Configure button on CADRaster toolbar and choose the Snap tab. Check the Snap to raster active and Magnifying Glass active options. Check the following Snap modes: Intersection of raster lines and Corner of raster line. Make sure that the Magnifying Glass options Verify every snap trial and Keep on display are checked. Increase Pickbox size to 14, or so. Click the OK button. The Raster snap pickbox will be added to the AutoCAD’s cursor, indicating that the continuous snap to raster mode is active.

Click the AutoCAD’s ZOOM/Window button. Click the Suspend mouse input button (or press Ctrl+S) to release the mouse cursor control to AutoCAD, choose a zoom window containing the right lower corner of the building together with dimensioning lines.

Click the Suspend mouse input button (or press Ctrl+S) again to resume the snap to raster mode. (This kind of suspending is not needed to perform AutoCAD’s commands that do not require mouse coordinate input; e.g. to ZOOM/In simply click the appropriate button or type the command.)

While having the snap to raster mode active, type AutoCAD’s command Dist. Place the pickbox around one end tick of a vertical dimension line labeled 13.20 and click the left mouse button. The Magnifying Glass window pops up to show the result of snap to the intersection point. If the snapping cross position is correct, accept it by a right mouse button click. The corrected point coordinates will be transferred to the Dist command. Otherwise, place the cursor correctly inside the Magnifying Glass window and click the left mouse button. Accept the adjusted position by right click.

Repeat the same action for the other end of the dimension line. When we have done it, the measured distance was 14348 (mm), quite different from the 13.20 (m) label. You will get much better result when using office4.tif that you may have created doing the resizing or matching exercise described in sections below.

The usability of various snap modes depends heavily on the features of background raster images. It is recommended to use the Magnifying Glass to verify snap results visually and to correct it manually, whenever the automatic snap result is not satisfying.

Raster snap for color images

Lines and other entities of color images can be made of many colors in different shades, so some kind of filtering scheme is needed in order to let the snapping mechanism properly determine the boundaries or raster lines and areas. CADRaster offers an interactive Raster snap color filter tool that lets the user define and examine adequate color interpretation, before it is used for snapping purposes.

Start CADRaster and open grudz.tif, a color map that contains some features, like roads and forest areas, suitable for color-sensitive snapping. Click the Filter button on CADRaster toolbar or select Filter colors from CADRaster ribbon. Choose a color sample area containing a junction of main roads that drawn in red (if the pickbox size is inadequate, use OTM/Snap... and choose a different one). The Snap/Trace Colors Filter dialog shows two windows, Colors sample and Filtered image example, that allow for further zooming in and out, if necessary.

In the Colors sample window click those pixels in different shades of red that belong to the main road line. All pixels of the same color get marked by white dots, the counter of colors in filter increments, and the Filtered image example window shows the filtered image; clicking inside this window toggles between color and black and white presentation. Clicking once more at a selected pixel in the Colors sample window removes its color from the filter; you may also use additional control buttons.

After having a color filter defined, click the OK button to close the Snap/Trace Colors Filter dialog, then activate snap and set Magnifying Glass options. Try snapping to different features, the centerline or intersection of the roads, or the edge of the forest areas.

Scanned grudz.tif is a full color image, so a good filter definition for the main roads may require up to 12 colors, the forest areas drawn in various shades of green, may take more than 20 colors, possibly collected from a number of samples. Needless to say, your snapping results will be only as good as the colors filter’s ability to retrieve a complete image of interesting entities, and only those, from the background. Furthermore, some color images will simply not contain any suitable entities to snap to.

Filter colors selections may be saved and loaded when needed again using Save and Load buttons in the Snap/Trace Colors Filter dialog.

Cropping and changing page size

Cropping may be the most common raster editing operation, as the scanned images usually contain oversized margins, usually filled with dirt, that need to be cut off. Equally often you might need to remove old drawing borders and other parts that happened to be located closer to drawing’s margins.

Click AutoCAD’s Open button and choose office.dwg, and after that, click CADRaster’s Open button and choose office2.tif. Click AutoCAD’s Zoom all button, if necessary, and you should see a hybrid drawing as below.

Suppose that the only part of the scanned drawing that you need for your project is the floor shown between dimensioning lines. Texts on the right side may be removed and the scanned image extents may be actually smaller.

Click the Crop, Define Page on CADRaster ribbon or Crop/Page button on the CADRaster toolbar and choose Crop rectangle from OTM options. (If OTM does not pop up, it means that the command has been used before, so you must use OTM hotkey (default: Ctrl+RightClick) to get OTM on the screen).

Define a rectangle encompassing this part of the scanned drawing that you want to have and accept the Crop rectangle command with a right click. All unwanted parts get cut off and the scanned image will get smaller, as shown below. Click the CADRaster’s Undo button to reverse the changes, or exit AutoCAD/CADRaster without saving anything.

Aligning and resizing scanned images

In one of previous exercises we have used the background of office.tif in order to create a new design by clearing some areas and adding new elements drafted in office.dwg. The resolution, scale and orientation of the background image were correctly defined, but the original drawing may be not to the scale and the scanning process may have produced a skewed image with distorted size and proportions.

Start CADRaster, use AutoCAD’s Open command and choose office2.dwg. This vector drawing contains a polygon drawn to the nominal dimensions of an office building. Click CADRaster’s Open button and choose the office.tif file from the DOC subdirectory. You will easily see the difference between vector-defined outline and the corresponding scanned image, as shown in the figure below.

You may use AutoCAD’s command Dist to check that the distances on the scanned image are not according to horizontal and vertical dimensions that are shown on the image. If the scanned image is needed as a background for any kind of precision drafting, it must be dimensionally matched to its reference dimensions, and that may require independent X & Y resizing.

Before we resize the image, however, it is recommended that the scanned image is aligned either horizontally or vertically. In this exercise we will use Magnifying Glass, so click the Configuration button and check on the Magnifying Glass tab Magnifying Glass active, Pop up on hot key pressed and Keep on display options. To avoid conflicts with AutoCAD’s osnaps, define F12 as Current hot key - simply select it in it's box and press F12.

Make sure that office.tif is selected for editing. Click the Rotate button on CADRaster ribbon or Rotate/Align button on CADRaster toolbar. If necessary, use OTM hotkey (default: Ctrl+RightClick) and choose OTM option Align. In order to align the whole image so that the left wall is vertical, define two points at its edge. First, place the cursor at the outside edge near the left lower corner of the building, click F12 (Magnifying Glass hot key) to pop up Magnifying Glass, click exactly at the wall’s edge and if the picked point position looks good, accept it with a right mouse click. Repeat it for the Second point of reference line at the left upper corner of the building. Accept the Vertical alignment and the Align command with right clicks. The visible effect of alignment will be rather small, as the image was skewed only a little, but you may notice that some horizontal and vertical raster edges are now sharper. Save the aligned raster image as office4.tif.

Next, we will move the raster image, so that its left lower corner corresponds to the left lower corner of the reference vector data. Click the AutoCAD’s ZOOM/Window button and choose a new window around the left lower corner of the building, as shown in the figure below.

Click the Move button on CADRaster ribbon or toolbar. Use the Magnifying Glass as before to define Base raster point exactly at the intersection of reference lines at the left lower corner of the building. Then, press Shift+RightClick, choose AutoCAD’s Endpoint and snap to the left lower corner of vector reference polygon to define Destination point. Accept the Move operation by a right click. The left lower corner of the building’s wall should move to the desired position. If you are not satisfied with the result, click the Undo button on CADRaster ribbon or toolbar and repeat the Move command.

The scanned image, now aligned and moved to the correct position, is apparently too large when compared to its reference vector data. Click the Match or Resize button. If necessary, use OTM hotkey (default: Ctrl+RightClick) and choose OTM option Resize. The left lower corner is at the correct position already, so we will use it as Base raster point - its position will be not changed by the Resize operation. Press Shift+RightClick, choose AutoCAD’s Endpoint and snap to the left lower corner of vector reference polygon again, this time as the easiest way of defining Base raster point that we have moved there previously. To define Raster reference point use Magnifying Glass and click exactly at the intersection of reference lines in the upper right corner of the image (just under the J in a circle sign).

You may now drag the Raster reference point to its Destination point but, since we have the vector reference polygon ready, the easiest and most correct way is to press Shift+RightClick, choose AutoCAD’s Endpoint and snap to the right upper corner of vector reference polygon.

Accept the Resize command with a right click. After resizing the scanned image should quite exactly match its vector reference data, so that further drafting on its background may be done directly in AutoCAD’s world coordinates.

Click the Save button on CADRaster ribbon or toolbar.

Matching raster images and vector drawings

The Resize procedure described in the previous section is quite simple to understand but not so simple to execute, since it involves a number of steps, like Align, Move and Resize, which are needed to achieve desired results. Providing that we have sufficient reference data, the same and even better results may be achieved using just one command Match that provides the simplest possible interface to powerful Tessel Systems CALIBRATOR.

As in the previous section, open office.tif and office2.dwg. We want to get the best possible match between the four corners of the vector reference polygon and the corresponding corners of the raster image.

Click the Zoom Document on CADRaster ribbon or Zoom whole doc button on the CADRaster toolbar. Click the Match/Resize button. Use OTM hotkey (default: Ctrl+RightClick) and choose OTM option Match. For each corner of the scanned floor drawing define Raster point by placing the cursor close to the corner, pressing defined Magnifying Glass hot key and picking the intersection of reference lines at that corner, as shown below.

Accept each Raster point by a right click, press Shift+RightClick, choose AutoCAD’s Endpoint and snap to the corresponding corner of the vector reference polygon.

After defining matching vectors for all four corners, accept the Match command by a right click. After the raster image is recalculated you should be able to see that this simple and quick operation has produced quite a perfect match at all four corners. Let's try to check what such simple to do a matching operation is worth. Click the Configuration button on the CADRaster ribbon or toolbar and check the Snap to raster active, Intersection of raster lines and Corner of raster line options on the Snap tab. Zoom/window so that the dimensioning line segment on the right lower side of the building is well visible, as shown above. The dimensioning text on the image says 13.28 (13.28m = 13280mm).

Type AutoCAD’s command dist and left click at the dimensioning line’s ticks placing them inside the raster snap cursor. Accept each snap with a right click. AutoCAD reports Distance = 13278. Definitely not bad a result as for an A4 copy of an A3 drawing that was faxed to Tessel Systems years ago by a German customer, and then scanned on a desktop scanner.

Calibrating scanned drawings

Important

This function works only for CADRaster PRO only

The same CALIBRATOR machinery that has been put to work under deceivably simple cover of the Match command may be unleashed with its full power for more demanding jobs. Let's try to calibrate a scanned drawing of a building that has more irregular shape.

Click the Open button on the CADRaster ribbon or toolbar and choose building.tif. Open building.dwg in AutoCAD - it contains a red polygon that defines the correct dimensions of the building in the world coordinates. The scanned drawings is correctly orientated and has a reasonable size since its parameters, like scale and units, have been defined properly, as it may be checked by clicking the Document Properties button, as shown above.

Our task is to match all six corners of the scanned building drawing to the corresponding polygon corners with numerically controlled accuracy.

In order to make the calibration process more convenient we will first move the raster image possibly close to its correct position. Click the Move button and pick the left lower corner of the scanned drawing as a Base raster point simply by left-clicking at it. Then move the cursor to the left lower corner of the vector polygon and left-click at it to define Destination point. This is just a preliminary move which precision does not have any influence on the calibration results, so no snapping or Magnifying Glass is needed. After moving the raster image it should correspond quite well to the reference polygon, as shown below.

If you wish you might zoom around corners and check that each one shows a different deviation from its correct position. Click the Calibrate button to show the Raster Calibration Parameters dialog. Push the Select base entities button, click the selection pickbox at the red polygon and finish selection by a right click. Push the Add entities based vectors button. The CALIBRATOR zooms automatically around the first corner of the selected entity with the calibration vector attached to it, i.e. having the target location already defined.

For each target define corresponding Raster point by placing the cursor carefully at the intersection of the outer boundary lines of the building (not the dashed markup line).

You may use OTM hotkey (default: Ctrl+RightClick) to get OTM that lets you change the AutoZoom level or use raster snaps, if necessary. You may also change the zoom level using the calibration Options button. If you choose Current, the automatic zooming will be done on the most recently used level that you may change by clicking Zoom in and Zoom out buttons in the Raster Calibration Parameters dialog.

After defining Raster points corresponding to all selected Target points, the Raster Calibration Parameters dialog presents complete numerical information concerning this calibration operation. Choose the Affine Calibration model from the list and check that Sqrt of mean square error that will remain after calibration is in the range of 0.03m (in world coordinates).

You may push the Net preview button and scroll through the list of Raster and Target points in order to evaluate visually differences between requested Target points and Calculated points depending on the Calibration model you choose. If you need to change something, you may delete points from the list or push the Edit vectors button, or double click at a list entry, and change the calibration vectors.

When you are satisfied with the calibration preview, click the Execute button in order to have the transformation applied to the image data. You may save the calibration report if you wish. After the calibration is executed you may still keep the Raster Calibration Parameters dialog on the screen in order to examine the results by scrolling through the list of calibration vectors. If you want to get closer to some point, double click at its entry and Zoom/window as close as its needed. Then right-click to get back to the dialog and use calibration Undo and Redo buttons to see that point before and after calibration. If you keep your Net preview button pushed, you should see that the Raster point is being moved by calibration to the end of the Calculated vector. To check or change calibration vector colors, push the calibration Options button.

Exit the Raster Calibration Parameters dialog by clicking the Close button. Optionally you may save the calibration vectors on file but, if you plan re-using them, remember to save the raster file just before doing the calibration, so that you may repeat the process using the saved vectors.

You may still Undo and Redo calibration changes using CADRaster ribbon or toolbar. If you want to be able to repeat this exercise without reinstalling demo files, exit CADRaster without saving the modified raster file, or push the Save as button on CADRaster ribbon or toolbar and give it a new name.

Calibrating scanned maps

Important

This function works only for CADRaster PRO

The same calibration technique described in the section Calibrating images applies to scanned maps. Maybe the most common difference is that while calibrating maps we can use regular networks of reference points more often than for other types of drawings.

Open hberg.tif file and Zoom/window around its left lower corner, so that the coordinates written there are legible, as shown below.

Click the Move button, pick the left lower corner of the map as Base raster point and type 3476100,5476200 as coordinates of Destination point. Again, this is just a preliminary move which precision does not have any influence on the calibration results, so no snapping or Magnifying Glass is needed. Accept the Move command with a right click.

Click the Zoom Document to show the entire map again, and the Calibrate button to show the Raster Calibration Parameters dialog.

Push the Define base net button and type in the Calibration net parameters describing a reference network corresponding to coordinate marks printed on the map as small crosses:

Horizontal vertices number: 8
Vertical vertices number: 7
Single cell width: 100
Single cell height: 100
Net insertion point (x,y): 3476100,5476200

Push the Create button and check if the created net looks as shown below, i.e. in this zoomed out view goes practically right through the marks.

Press the Add net-based vectors button. The CALIBRATOR zooms automatically around the first corner of the defined net with the calibration vector attached to it, i.e. having the target location already defined.

Since the coordinate marks on the map have the regular form of small raster crosses, we are going to use raster snap to intersection. Click the Configuration button on CADRaster ribbon or Configure button on the CADRaster toolbar and check the Snap to raster active and Intersection of raster lines on the Snap tab. On the Magnifying Glass tab check the Magnifying Glass active, Verify every snap trial and Keep on display options.

For each target define corresponding Raster point by clicking the snap cursor at the corresponding coordinates mark and accept it with a right click. You may use OTM hotkey (default: Ctrl+RightClick) to get OTM that lets you change the AutoZoom level, if necessary.

Magnifying Glass pops up for every snapped coordinate mark (intersection) and provides instant visual verification. Do not correct errors smaller than half a pixel - it does not have any statistical meaning and often is very subjective. Correct only those points that are obviously wrong, usually due to interference of some other lines with the cross mark, as shown below. You should need to correct no more than 5-6 snaps, and only at one point Raster snap will not find the intersection at all.

Simply pick a new position for the snap cross in the Magnifying Glass window and accept with usual right click. If you accept by mistake a wrong point, use OTM hotkey (default: Ctrl+RightClick) and choose the OTM Previous option to go back to it and redefine it.

After defining Raster points corresponding to all 56 Target points of the net, the Raster Calibration Parameters dialog presents complete numerical information concerning this calibration operation. Choose the Bicubic Calibration model from the list and check that Sqrt of mean square error that will remain after calibration is in the range of 0.219m (in world coordinates).

When using Calibration models higher than Bilinear you must look at the calibration preview before executing it. Insufficient or badly selects calibration data, e.g. colinearly placed Target points, may result in perfectly small residual error and very bad deformation of the raster image between calibration points. Press the Zoom raster and Net preview buttons. Calculated net should show only small and smooth deviations from the Reference net, as shown below. To check or change calibration nets colors, press the calibration Options button.

When you are satisfied with the calibration preview, click the Execute button in order to have the transformation applied to the image data. You may save the calibration report if you wish. After the calibration is executed you may still keep the Raster Calibration Parameters dialog on the screen in order to examine the results by scrolling through the list of calibration vectors. If you want to get closer to some point, click at the Zoom in button in the Raster Calibration Parameters dialog. Then use calibration Undo and Redo buttons to see that point before and after calibration. If you keep your Net preview button pushed, you should see that the Raster point is being moved by calibration to the end of the Calculated vector. To check or change calibration vector colors, push the calibration Options button. Exit the Raster Calibration Parameters dialog by clicking the Close button.

Zoom/window around the left lower corner of the map, as at the beginning of this section (you may need to suspend Raster snap by clicking the Suspend mouse input button, and then releasing it after zoom). Snap to raster mark (intersection) at the left lower corner, as shown below.

All coordinate marks on the whole area of the calibrated map will show correct coordinates with accuracy better than 0.2 m in world coordinates. At 1:1000 scale it means that the calibrated image accuracy is better than 0.2 mm across the entire map.

Tracing raster lines

Important

This functionality is available only in 32-bit version CADRaster PRO

As every specialized tool, CADRaster’s semiautomatic raster lines tracer preferably should be used only for jobs it has been designed for. One kind of drawings that are suitable for this sort of tracing is isolines maps. Open isolines.tif, click the Configuration button on CADRaster ribbon or Configure button on CADRaster toolbar and clear the Raster snap active option on the Snap tab, so it will not interfere with tracer. Check the Use raster line widths option on the Tracer tab. Close the CADRaster Configuration dialog by clicking OK.

Click the Raster trace button on the CADRaster toolbar and use OTM hotkey (default: Ctrl+RightClick) to select OTM options Polyline, Line profile\Soft curves, View points and Optimize merging. Click at the beginning of one isoline and wait until Tracer stops at the end, an intersection or a break in the line. Click at the next segment to continue the polyline, or RightClick to finish it. Choose Repeat if you want to trace one polyline after another.

Cut/Copy/Paste editing

Important

This function works only for CADRaster PRO.

CADRaster Cut, Copy, Paste editing is most often used for moving around selected raster areas within the same image or for transporting them between different raster images. CADRaster treats rectangular or polygonal areas of raster image in a way similar to AutoCAD blocks. It operates in world coordinates, defines the insertion base point, and allows for rescaling and rotation while inserting raster blocks.

Open office.tif. Suppose that we need to create an insert showing the stairway scaled up two times. Click the Copy raster button on the CADRaster toolbar. If necessary, use OTM hotkey (default: Ctrl+RightClick) and select the Rectangle and Clipboard OTM options. Pick corners of a rectangle to copy and the Insertion base point as shown in the figure below. Right click to accept the Copy raster command .

Click the Paste raster button on the CADRaster ribbon or toolbar. If necessary select the Clipboard OTM option or push the Clipboard button in the Paste from dialog. Pick an Insertion point in the empty area on the right side of the drawing, type in 2 for both X and Y scale factors and type Enter to accept no rotation. Type Enter or right click to accept the Paste raster command. CADRaster inserts a scaled up image that you have copied to the Clipboard.

Try other options of cut, copy and paste commands, e.g. using polygonal areas and pasting from files.

Inserting vectors to raster

Important

This function works only for CADRaster PRO

When you need to create new lines or symbols in order to modify the existing raster image, you should use normal AutoCAD drafting commands, symbol libraries etc. The resulting DWG may be then kept as a component of a composite document, as shown before, or vector entities may be inserted into the raster background in order to create a modified single raster file.

Open office.dwg and office2.tif. Click the Insert vectors button on the CADRaster ribbon or toolbar. Pick corners of a rectangle surrounding the new building components drawn in vectors, as shown in the figure below. Right click to accept the Insert vectors command.

CADRaster uses its CADRaster Rasterize plotter interface to output vectors inside the rectangle, rasterizes them using parameters compatible with the background raster image and inserts the rasterization product exactly under the source vectors. Zoom window to see details of inserted vectors around the Freight elevator text and symbol, as shown in the figure below.

Important

Please remember, that in oder to use this command you need to add a Plotting output device named CADRaster Rasterizer. See the section called “CADRaster and AutoCAD”.

Under close zoom you may need to regenerate the vector drawing in order to get precise shapes - vector lines should appear as centerlines of their raster counterparts. The rasterized lines and texts are thicker, since CADRaster applies its plotter interface pen settings, exactly as if making a plot. The apparent precision of rasterization would be even better for a higher resolution of raster background image.

Rasterizing whole vector drawings

CADRaster rasterization engine may be used to rasterize whole vector drawings to a selected raster format, either monochrome, grayscale or color. This process is often used to create images of DWG drawings in raster formats that may be easier to distribute or maintain in archiving systems and other applications that do not need to access vector entities.

If any raster file is open, click the Close button on the CADRaster ribbon or toolbar. Open an AutoCAD sample drawing, e.g. db_sample.dwg or any other 2D drawing from AutoCAD’s SAMPLE subdirectory. Click the Create raster button on the CADRaster ribbon or toolbar.

Enter the following parameters into the Create New Image dialog:

Window tab

check Window
type in Scale 1:1000 (if the image is too big it will automatically adjusted).
choose Drawing units meter

Resolution tab

choose Resolution 600 x 600 dpi
choose Image size units pixel (or any other)

Color tab

choose Black and White

Click OK and give the new image file name db_sample.tif. Choose Compression mode CCITT Group 4 and click OK again.

Important

Please remember, that in oder to use this command you need to add a Plotting output device named CADRaster Rasterizer. See the section called “CADRaster and AutoCAD”.

After the rasterization process is completed, open db_sample.tif - it should appear as a background image exactly corresponding to its DWG original, just drawn in thicker black lines. Click the Document Properties or Control doc button and choose the Color tab. Select a light color, e.g. 41, so that all vectors may be easily seen on the raster background. Examine the results of rasterization by zooming closely at some places, as shown in the figure below.

Check the size of db_sample.tif) and compare with db_sample.dwg - due to the high Group 4 compression this high resolution raster image is much smaller than its DWG original.