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Digitizing Existing Plan & Profile Drawings
You can easily use existing Plan & Profile (P&P) drawings to create new PLS-CADD models. This TechNote describes the necessary steps in detail below. Existing P&P drawings can either be electronically scanned manual drawings or drawings from another CAD system. Once familiar with this technique, the user should be able to fully duplicate an existing drawing in PLS-CADD in less than one hour per drawing and usually much faster than this on a production basis.
In general, the steps are to obtain a scan of the manual drawing in a BMP, TIFF, or ECW format (TIFF is the preferred format). PLS-CADD does not support JPEG, so you will need to convert any JPEG images to one of the supported formats (you can easily convert it to a TIFF by opening the JPEG in just about any graphics program and executing a File/Save As a TIF image).
You can also obtain a TIFF from a PDF, should your existing P&P drawings already be scanned into a PDF file. Adobe Acrobat does this using the File/Save As command and there are also a host of "PDF to TIFF" freeware and shareware programs available on the Internet.
Once you have an electronic image of your drawing for use in PLS-CADD, you simply attach the drawing, calibrate ("rubbersheet") the drawing, and then use the heads-up digitizing commands to duplicate the drawing.
Step-by-step instructions with some helpful tips are as follows:
A video showing this process is available here. Note: this video is large (36MB) and may take a while to start playing or download.
- Open PLS-CADD.
- Choose File/New/PLS-CADD
- Choose the desired directory you wish to create the project in and the desired project name, using a .PFL extension for the project name (i.e. "Digitize.pfl").
- Select Drafting/Attachments/Attachment Manager from the menu.
- Once in the Attachment Manager, click the Attach button, and find the image you wish to digitize.
- You may receive a warning about georeferencing being in the currently selected unit system. We can ignore this in this case and select the OK button.
(However, if you are attaching other images that are georeferenced, you should be in the same unit system as the image (select in File/Preference) so that your images will be properly georeferenced.)
- Once the image is read, you will be in the Bitmap Options dialog box. You will see some parameters for the drawings, but these do not need to be modified.
The only thing you will need to change here is the view in which to attach the image. The default view selected is the Plan View. You will need to change this to the Profile View since we are interested in digitizing the profile at this time.
- You will be prompted if it is okay to reset the values of the drawing so that it is attached to the end of the profile. It is usually best to click the Yes button here, but is not necessary.
- It would appear at first that nothing has happened, but if you inspect the graphics, you are most likely in the Plan View. Since we attached the image to the Profile View, we will need to open that view to see the image. Select Window/New Window/Profile View from the menu.
- You should now see your scanned image on the screen. You may need to select View/Initial (or select the INIT toolbar button) to center it on the screen.
- If you selected "No" in step 8 above, or if your scanned drawing is not in the same aspect ratio (horizontal scale to vertical scale) as what you have selected in PLS-CADD, there is a chance that your drawing will not look correct.
You should use the View/Scales, Rotations, Panning/Profile View Aspect Ratio and change it so that your drawing appears correct. You would most likely select 1 and 1 if you had chosen "No" in step 8.
- You may need to "Initial" the screen again (see step 10).
- There is a very small chance that your image may not be drawn properly if your video driver cannot handle large images. If your image is garbled or "dirty" select Drafting/Attachments/Image Drawing Options, and check the "Draw images manually…." option. This will use the PLS-CADD routines to draw the images instead of your video driver. If your image appears correctly, you should not select this option as it draws slower than the hardware accelerated driver will.
- We are now ready to calibrate the sheet. Select Drafting/Attachments/Calibrate Sheet. Since you may have more than one drawing attached, you will be presented with a dialog box to select the drawing you wish to calibrate. Select it from the list and hit the "OK" button. (You can also simply double click on the drawing name as well.)
Note for sheets going from right-to-left: Before proceeding with calibration you should first go to File/Preferences and make sure to select Equation Stations for the Stations Displayed.
Then in Terrain/Station Equations input a station equation for the leftmost pole (which means you should have attached the leftmost sheet in step 5).
The station equation will be true station of zero, equation station of the leftmost pole and then forward direction is no.
You may now proceed with the calibration.
- You will see a crosshair icon on the screen and the status bar on the bottom of the screen will tell you that you are in the Calibrate Sheet mode, and that you should "Click on left of station axis".
- You should find a horizontal line on your profile that you will be able to click on two points at each end of the drawing (the points should be as far apart as possible) and be able to type in the stations of each point. Having a hard copy of the drawing available while doing this would assist in this effort, but it is not necessary.
- Click on the left most point of this horizontal line. As you can see, it will be difficult to locate this point when looking at the extents of the drawing, so you should zoom in on it. However, if you select the View/Zoom command now, you will abort the Calibrate Sheet command.
This is not a problem as you can simply start back on step 14 again after you find this point. You can use the "+" and "-" toolbar icons or use the "+" and "-" keys on the keyboard (you don't need to use the Shift button to get the "+" - just hit the "=" key) and use the scroll bars on the bottom and side of the screen or use the up-down-left-right arrows on the key board to get the drawing to an acceptable level of zooming on this left station point.
- Simply left click on this point on the screen now. You will be prompted to type in the station of the point you just selected. Don't forget to add the "00" if you are working with an older style drawing that uses the "+00" format for stationing.
- The status bar at the bottom will now instruct you to "Click on right of station axis". Use the scroll bars or the keyboard arrows to get over to this point. If you use a command (such as Zoom or Inverse Zoom) to do this, you may abort the calibration process and will have to start back at step 14 again. Tip: you can hold down the "shift" key on the keyboard and use the mouse to "fly" across the drawing as well.
- Once you find the right most station of the drawing, click on it, and type in the station of that point when prompted.
- The status bar at the bottom will now prompt you to "Click on first of two points with known elevation." Similar to the stationing, you should find two points with as much as separation as possible with known values and in a straight line above each other. Using the commands as described in earlier steps, find the first of these two points and click on it. Enter the elevation when prompted.
- Finally, the status bar at the bottom will prompt you to "Click on the 2nd of two points with known elevation." Find this second point, click on it, and enter the elevation when prompted.
- You may be prompted with a question regarding rotating your drawing. Odds are that your drawing wasn't scanned perfectly horizontal, and a small rotation may be required. You should click the "Yes" button for this step.
- You are now done with the calibration process. You will most likely need to initialize your drawing (select the INIT button in the toolbar) to see where your drawing has relocated to. If you changed the aspect ratio above, or if your drawing doesn't match the aspect ratio you have selected in PLS-CADD, you will need to change that accordingly as described earlier in step 11. Initializing the view again (INIT button on the toolbar) should show your drawing correctly with the correct aspect ratio.
- You should now confirm that the calibration is correct by comparing the stations and elevations of some points on the screen with those in the drawing (you can use the View/Distance Between Points command).
- You are now ready to begin digitizing your drawing. When digitizing, you will be prompted to enter a feature code. It would be a good idea to now load your standard feature code file if you have one. If you do not have one, we have a suggested one (along with a survey specification) on our website here. To load a feature code file, simply go to Terrain/Feature Code Data/Load FEA File…
- To begin digitizing, use the Terrain/Edit/Add PFL Point command. You will have a crosshair icon and there will be a dialog box in the upper left hand portion of your screen to select additional information about each point you select. Select the Feature Code of each point you wish to digitize, as well as any other required or desired information.
We suggest beginning with the centerline profile, select the feature code accordingly, and start clicking at various points along the profile. Points need not be selected continuously, and in fact, it may even be helpful to pick points far apart and then pick intermediate points as necessary to provide the best fit for the profile.
If there are any P.I.s on the drawing, be sure and include the value in the Angle cell before clicking on that point. (Positive values are right turn angles and negative angles are left departure angles.) Side profiles or other points not on the centerline of the survey can easily be defined by using the Offset value (points on the left side of the profile, looking ahead on line, are negative and points on the right side of the profile are positive). Be sure and digitize points for the conductor attachment points and midspan sags so that you can use the Structure/Move On and Sections/Graphical Sag commands.
- Additional P&P drawings can be attached, calibrated and digitized in the same manner by just continuing on. You may want to attach all the images first, then the calibrate them, then digitize them, or you many want to attach and calibrate each sheet and then digitize all of them at the same time. You may also want to take advantage of showing and hiding the drawings so that it will be easier to work on each drawing.
- Snap your standard structures in and snap your conductors to the points you've digitized.
- Once you have completed the digitizing, you may want to orient the project into your desired coordinate system (i.e. State Plane) by using the Terrain/Edit/Edit Origin command, and specifying the coordinates of the first P.I. and azimuth of the initial departure. You can easily convert your project into an XYZ project by doing a File/Save As and using the name of your project with an XYZ extension (i.e. Digitize.xyz).
You can now merge points from a new survey to incorporate new crossings and other changes that may have happened since the P&P drawings were last updated.
You can further enhance your P&P drawings in PLS-CADD by using a graphics program (such as Paint Shop Pro) to crop the plan views out of the scanned drawings and attach them in the plan view.
Using the process as described in our P&P Drawing preparations here you can prepare complete P&P sheets that will emulate your older manual drawings with the outstanding advantages of having all of your lines modeled in PLS-CADD.
An example of such a drawing is available for you here.
Our technical note on Working With Image Attachments in PLS-CADD can be helpful when scanning drawings.
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