Taking Advantage of the Explosion in Online Imagery with Autodesk Raster Design.

Transcription

1 11/28/2005-1:00 pm - 2:30 pm Room:Osprey 2 [Lab] (Swan) Walt Disney World Swan and Dolphin Resort Orlando, Florida Taking Advantage of the Explosion in Online Imagery with Autodesk Raster Design. Gary Stephenson - Autodesk and Bill Hamilton (Assistant); Harold Litzenberger (Assistant); Leonardo Asuan (Assistant) GS13-1L Yes, the imagery is free, or inexpensive, but how do you make it useful for your project? Don't pass up the opportunity to learn hands-on how to work with exciting aerial photography, satellite imagery, and digital map and DEM data. In this class you will learn just enough about coordinate systems to transform this online data to your own system. You will also gain confidence in cropping, merging, and resampling imagery as necessary. Finally, you will learn some tips and tricks for using these image types to create eye-popping presentations. About the Speaker: Gary has been active in the imaging industry for 20+ years in a variety of roles. His application experience ranges from medical imaging to document imaging and from AEC to GIS. His AutoCAD experience began with Image Systems Technology, Inc. as product manager for the pioneering CAD Overlay GSX. For Softdesk, Inc., Gary continued to focus on imaging solutions for AEC, developing datasets and tutorials, training resellers, customers, and Softdesk personnel in imaging applications. He now works as a program manager for imaging products including Autodesk Raster Design. Gary holds M.B.A. and B.S.E.E. degrees from Rensselaer Polytechnic Institute in Troy, New York. gary.stephenson@autodesk.com

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3 Introduction In this lab you will be creating a composite display of several images in an area of upstate New York. All of the data used was obtained off the web for free. You will be using a combination of Map and Raster Design to accomplish this. The majority of the lab exercises in this class will involve georeferencing the image data to a common global coordinate system used by your drawing. Along the way you will gain an appreciation for several commonly used coordinate systems, learn how to validate your transform results, and see ways to combine these different image types for impressive results. You will also learn in this class a bit about using REM tools and Image processing to refine your imagery once you ve obtained it. After this class you should feel comfortable working with any downloaded imagery from anywhere in the world for use in your own projects. Download Data The following files have already been downloaded off the web and un-zipped if necessary to your lab machine. They are located in their respective directories at C:\datasets\GS13-1L. The paths are provided in case you want to explore these sources after class. Index Maps: ftp:// USGS Topo: DEM: DOT Quad Maps: Color Aerial Imagery: To be downloaded from later when proper tiles are determined. Satellite Imagery: (I ve found that I can only get here if I paste this link into my browser instead of following it with a Ctrl-click). Zoom into the upstate NY region. You will see the file designation N_18_40_2000. Enable the radio button for Select Image and then click on the image in the display. You will get a new window showing just the above image. Once there, click on Download MrSID Image MB 2

4 Setup the Index Drawing While this step is not explicitly an Image operation, you may find that image data on the web has shape file information associated with it. In this case, the shape information is a key to finding which image tiles we will want to download out of an entire collection. In other cases you might find related Shape information like cadastral boundaries, fire and zoning districts, wetland designations and so on that you can use with your project. Step 1: Step 2: Use File Open and navigate to C:\datasets\GS13-1L\DWG. Open Index.dwg found in this directory. You won t see anything in the drawing after you open it. Note that a layer is defined in the drawing for the shape information and that the global coordinate system is set to New York NAD83 East zone Feet (NY83- EF). How do you know this is the global coordinate system? Use Map Tools Assign global coordinate system to get the dialog: When you are done checking, click Cancel to return to the command prompt. For simplicity sake, we re keeping our project in the same coordinate system as the shape information but this is not required. Step 3: Use Map Tools Import, select files of type ESRI Shape (*.shp), navigate to C:\datasets\GS13-1L\Index Maps, and select the file sar_sp_col_index04.shp. Click OK. In the resulting Import dialog. click on the <none> in the Data column. Click on the resulting expand icon to get to the Attribute Data dialog. Once there, select the radio button for Create object data. Note the Object Data box is now populated with the corresponding table file. Click OK. Check the box for Import polygons as closed polylines. The dialog should appear as below: 3

5 Step 4: Click OK on the Import dialog. Your drawing should now appear as below containing a vector grid showing where imagery is available. Insert Topo Reference Map Step 1: Use Image Insert and navigate to the C:\datasets\GS13-1L\USGS Topo directory. Highlight the Topo map image o43073a7.tif. You should see a preview of the topo map in the Preview pane. Make sure under Insert Options that the radio button for Insertion dialog is pressed and that the check boxes to the right are all checked Off. The dialog should appear as below: 4

6 Step 2: Step 3: Click Open. You will now be presented the Image Insertion dialog containing four tabs. Switch to the Source tab. Make sure the Correlation source drop down is using Image File correlation. Take a look at the other possible correlation sources such as World file and Tab file. Note that when they are selected, less information about the image file is reported. With Image file correlation selected, the dialog should appear as below: Image File correlation works best for this image since the image file is actually a GeoTIFF file which contains the image coordinate system and units reported in the lower part of the dialog. 5

7 Step 4: Switch to the Transform tab. Since the drawing and image coordinate systems are different, we ll need to perform a coordinate transform. Check the box for Transform to Drawing s Coordinate System. In the Select Category from List drop down box, scroll to near the bottom of the list to find and select the UTM, NAD27 Datum, matching what was reported by the image. With that selected, scroll through the Coordinate systems in category list box to find, and select Zone 18N Meter. (Remember we knew the units were meters from the Source tab). The dialog should now appear as below: Step 5: Now move to the Insertion tab. Notice how the insertion point is dramatically different that it was on the Source tab. You can momentarily switch back to the Source tab to compare if you wish. Bottom line is that the Source tab shows the insertion point in the images coordinate system and the Insertion tab shows where the image will be inserted after being transformed to the drawings coordinate system. Click OK to finish the insertion process. After the coordinate transform processing finishes, your drawing should now look as below: 6

8 Step 6: Step 7: Step 8: Now we ll verify that the Topo is inserted correctly. This is important because we ll be using the Topo as a reference for the other images we insert later, plus I do it just to gain confidence that I am on the right track. Zoom into the scale area of the topo map. Check the scale by using the AutoCAD Dist command and picking points at the extremes of the foot scale bar (make sure AutoCAD object snap is turned off because otherwise you may be erroneously measuring from the image grid). You should get something close to 7,000 feet. This is a good sign. Now, Pan to the lower left map border area and look where State Plane coordinates are labeled Feet. Put your cursor over this point and look at the AutoCAD coordinates. Is the X coordinate reported as something close to 630,000? Oops, you re probably seeing something around 668,000 instead! What s wrong? Pan to the legend area at the lower left of the Topo map. Read about the map projection. Ahh, the map is reporting State Plane coordinates in NAD27 not the NAD83 our drawing is in. In order to check our coordinates in NAD27 we ll use Raster Data Query. Use Image Raster Data Query. Once this window is up, notice that as you move your cursor, its coordinates are reported in the dialog. These coordinates match those reported by AutoCAD since we have not setup a transform for the cursor coordinates yet. To do so, click on the Choose Transform icon in the upper left of the dialog next to where it says not Set. In the resulting dialog we want to set our cursor coordinate system which for this Topo map is NY State Plane NAD27 east zone Feet. For the category choose USA, New York. Find and select NAD27 New York State Planes, East Zone, US Foot in the Coordinate Systems in Category list box. The Raster Data query window should now look as below: 7

9 Step 9: Now move your cursor over the State Plane marker on the bottom border. Now our X coordinate of 630,000 agrees. Just for grins, check the Y coordinate on the lower portion of the left border. Good, close to 1,100,000 right? Our confidence is building and we know the Topo map has been inserted correctly. Step 10: While we have the raster data query active, click on the Select Image icon just to the left of where it says Image name. Select the Topo image frame. Now see that as you cursor over the image that the pixel values from the image are reported along with the coordinates. You will find this to be particularly useful when working with Elevation models (DEM s) because you will be able to read off the elevation of any particular point in the drawing using the coordinate system of your choice. Close the Raster Data Query window. Insert Color Images Step 1: Highlight and pick the green rectangle surrounding the fairground near the lower left corner of the Topo map as shown below. 8

10 Step 2: Step 3: Right-click and select Properties from the bottom of the resulting shortcut menu. Scroll down to the bottom of the properties dialog and find the entry for FILENAME. This is the file that will cover this area. Normally you would go to the web at this point to either bring this file local or insert it directly. Due to the large number of participants in this class I have already brought the files you will need local so we don t swamp the web site. The web site also provides the information that these images are in NAD83 State Plane coordinates. Step 4: Step 5: Step 6: Step 7: Step 8: Step 9: Use Image Insert, navigate to the directory C:\datasets\GS13-1L\Color Aerials and highlight the top sid image e_ _12_07200_col_2004.sid. Leave the Insert Options as we had them before, and click Open. In the Image Insertion dialog Source tab note that the World file has been automatically picked up and that the coordinates presented seem reasonable for NAD83 State Plane based on our previous experience with the Topo map. Move to the Transform tab in the Image Insertion dialog. Note that the image is already in the drawing coordinate system so un-check the Transform box. Move to the Insertion tab. We should expect to see the same numbers here that we saw on the Source tab but we don t. Go to the Modify tab and note that the image has been assigned the units of meters when it is in fact in Feet. Change the Image units to Feet and click Apply. Moving back to the Insertion tab, the numbers look right and the image previews in the right spot. Click OK. Perform a similar insertion process for the second image, e_ _12_07200_col_2004.sid, which is the tile directly above the first. Note that this image comes in properly without any adjustments in the Image Insertion dialog because our earlier settings were remembered. Your drawing should now look as below: 9

11 Step 10: We are through with the grid for now, so turn off layer sar_sp_col_index04. We ve seen how to deal with images off the web that are in a different coordinate system than our project, but you can also run into situations where images because of their format aren t readily editable in Raster Design, and/or cover more area than needed and/or are composed of multiple, tiled images, and/or are at a much higher resolution than needed. The following steps will take you through dealing with these kinds of problems. The first issue we have to deal with in this example is that these aerial images are in a non-editable, Mr Sid format. You can always just Save-as the images to a more common, editable format such as Tiff, but we ll use REM operations in this exercise to perform double duty for us. Step 11: Start out by using Image Raster Entity Manipulation Create Region Circular. Create a region that bridges the two images but still stays within the confines of both. When the Image select dialog is presented, use shift-select to add the selection of the second aerial. The result should look like that below: Even though the result looks like a single REM region, there actually are two overlaid on top of each other, one from each of the images. Step 12: Using a Crossing window select both REM regions (only the regions) and Right-click. Off the resulting shortcut menu, click on Convert To Raster Image. You should see a result like below: 10

12 Step 13: You can now Erase the two original images saying Yes to detatch. Step 14: Right-click on the image and select Image Transparency. Turn transparency On. The image now looks as below: Step 15: To change the density of the resultant image to something more appropriate for our project, use Image Image Processing Change Density and select the newly created image. In the resultant Change Density dialog, enter 3.0 feet (approx 1 Meter) per pixel in the New Settings pane as shown below: 11

13 Step 16: Click OK in the Change Density dialog. Insert DEM Step 1: Use Image Insert, navigate to the C:\datasets\GS13-1L\DEM directory and highlight the p48elu.dem file. Leave the Insert Options as we had them before, and click Open. Notice we have an additional tab in the Image Insertion dialog. This is to accommodate setting up color mapping for datatypes such as DEM that contain floating point values. Step 2: Step 3: Move to the Assign Color Map tab of the Image Insertion dialog. Click on the Create new color map button which is just to the right of the drop down list of previously defined color maps. In the resulting Palette Color Map Definition dialog, in the Palette section, click Import Choose the USGS_DEM.pf palette file and click Open. In the Display Enhancements section check the box for Hillshade and set the Vertical exaggeration to 5. Check the box for Blend. The Palette Color Map Definition dialog should now appear as below: 12

14 Step 4: Step 5: Step 6: Step 7: Click OK. Move to the Transform tab of the Image Insertion dialog. Select the check box for Transform to Drawing s Coordinate System. Enter the coordinate system code UTM27-18 which corresponds to the system reported by the image. Click Apply to preview the insertion location in the drawing. Note that you will see just the image frame of the DEM encompassing the Topo map border. Click OK. Note that the DEM has obscured our aerial photos. Shift-left-click to bring up the Image Select dialog, highlight the aerial photo, and click OK. Now right-click and choose Image Bring to Front off the shortcut menu. The Aerial photo is now back on top and your drawing should appear as below: 13

15 Insert Bitonal DOT Quad Maps These bitonal separates of USGS quad maps are very helpful because they overlay nicely on other imagery. Raster Design can also be used to create workable separates from full USGS quad maps. Step 1: Step 2: Step 3: Step 4: Use Image Insert and navigate to the directory C:\datasets\GS13-1L\NYS DOT. Highlight the p48plan.tif file. Leave the Insert Options as we had them before, and click Open. In the Image Insertion dialog Source tab, note that Image file correlation is selected automatically and that the image coordinate system and units are reported. This information is available because this file is a GeoTiff file. Move to the Transform tab of the Image Insert dialog. Insure that Transform to Drawing s Coordinate System is selected. Set the image coordinate system to be UTM NAD83 Zone 18 North Meters (UTM83-18) as reported. Click Apply and verify that the image previews in the correct location in the drawing. Click OK. 14

16 Step 5: After Coordinate transform processing is complete, zoom to the extents of the aerial images we inserted earlier and see how the DOT plan map overlays on the photos. It should look as below: Exercises Left to the Reader Insert Satellite Imagery Download and insert the satellite imagery found at the site above. Move it behind the rest of the imagery and verify its proper registration. Crop the satellite image to cover a more reasonable area. Query the DEM Change the coordinate system Raster Data Query uses to Lat-Long. Use Raster Data Query on the DEM by selecting it as the active image for the query. Note how elevations are reported even though you may have your cursor over the Aerial photo and cannot see the DEM underneath. 15