Introduction This document outlines the procedures necessary for converting an AutoCAD Map drawing containing topologies to ArcGIS version 9.x and higher. This includes the export of polygon and network (line) topologies to the equivalent objects in ArcGIS. The example below will use a geologic map of a 1:24,000 USGS quadrangle as an example of how one could export map elements from AutoCAD Map 2002 to ArcGIS. In addition, examples are given on how to incorporate downloaded digital raster graphic (DRG) and digital elevation model (DEM) data with the ArcGIS project. In this example the Cheaha Mt., Alabama 1:24,000 quadrangle geologic map is used for reference. Unless otherwise stated all elements of the map use NAD27 datum. Preparing the AutoCAD Map File These steps will help prepare the AutoCAD Map 2002 drawing file for the most effective transfer of objects to ArcGIS:! Separate all drawing entities into logical layers. Linework symbols blocks inserted in the drawing with the measure command should be in layers separate from the polylines. For example fault contact teeth blocks inserted with the measure command should be in a layer named FaultLineWork.! Geological contacts should be classified in a network topology (named xx_contacts where xx is the quadrangle abbreviation) as: depositional or igneous contact = contact Faulted contact = fault Uncertain depositional or igneous contact = ucontact Uncertain faulted contact = ufault Object table name = LineCode Object field name = LineTypeCode Exporting Lithologic Polygon Topologies STEP 1: Preparing Closed Polylines Create a layer named ArcGIS_Lithology and make it the current layer. Load the polygon coverage and then select the menu option Map > Topology > Create closed polylines. The Figure 1 dialog window will be activated. Note that the option to copy object data associated with the polygon topology to the new closed polylines must be selected (checked). The closed polylines should appear in the ArcGIS_Lithology layer after the OK button is selected. Check one of the closed polylines with Map > Object data > Edit object data to make sure that the object data has been copied to the closed polyline. Page 1 of 8
STEP 2: Exporting Lithologic Polygons This step is started by selecting the Map > Tools > Export menu option. The initial dialog activated by this menu selection requests the folder name for the export procedure- indicate your working folder under C:\ArcGIS_Data\XXX where XXX are your initials (You should create this folder before trying to export the topology). Leave the type of export file set to ESRI shape file (.shp). The next dialog displayed in Figure 2 allows you to choose the type of topology and indicate the object data that the shape file will inherit (Selection tab). In this case a polygon topology is being exported to a ArcGIS shape file format. Note that the closed polylines layer ArcGIS_Lithology is indicated as containing the entities that will be used to create the exported polygon topology. Do not click the OK button yet! Figure 3 displays the dialog activated by selecting the Data tab in Figure 2. This dialog allows you to choose the object data that will be attached to the exported polygon topology. Select the object data table XX_Lithology and the field LithologicCode where XX represents your quadrangle 2 letter abbreviation. In this example we are using CM. After the OK button is selected the required files are exported to the indicated folder. You can now run ArcGIS to load the shape file data. Start the process by starting ArcMap from the desktop. When ArcMap opens you should initially add the USGS DRG raster image to the project file so that the image can be used as a base map for reference. Do this by selecting the plus sign icon from the toolbar. You should verify that ArcGIS reports valid UTM coordinates for your quadrangle when you move the cursor over the base map area. You can do this by zooming in and comparing the UTM grid tic marks on the USGS base map to the coordinate readout of ArcMap (lower right-hand portion of application window). In addition you need to set the coordinate system for the entire project at this time. Right click on the layer title in the layer window, select properties, and then the General tab. Change the project title to Cheaha Mt., AL Geologic Map. Also set the reference scale to 1:24,000. In the Coordinate System tab select NAD27 UTM zone 16N coordinates in the list of predefined projections. Next indicate that you want to add another data layer by again selecting the plus sign icon in the toolbar. You should then see the a file open dialog- select the Lithology shape file that is in the folder you created for the ArcGIS project. Figure 4 displays the appearance of the ArcGIS drawing window after the lithology shape file is added to the project. Within ArcGIS, setup a color scheme for your polygons based on unique values of the data table items attached to each polygon- do this by right-clicking on the Lithology layer name in the left window pane. Select the properties link from the popup window, and then select the symbology tab. Figure 5 displays the ArcGIS symbology legend editor- click on the import button in the upper right portion of the dialog, and then choose the NAP_lgnd.lyr file provided Page 2 of 8
by the Project 2 download operation. The result of importing this legend should produce a result similar to Figure 6. Note that many of the layer entries on this quadrangle are not actually needed. To get an accounting of the used definitions click on the count heading in the right column. You can proceed to highlight any un-used definitions and used the Remove button to clean out non-used definitions. Save the modified layer as a separate file by clicking OK, returning back to the main ArcMap window, and again right-clicking on the Lithology name in the layer window. This time select the Save as layer file option. Save the file as cm-geo.lyr (or whatever is appropriate for your project). Making these edits will usually significantly reduce the number of lithology definitions present in the layer window, and this makes the project easier to manage. STEP 3: Exporting Contacts Before exporting contacts to ArcGIS you should make sure that each contact is part of a network topology named xx_contacts, and has attached to it a xx_contacts table, and that the LineCode field has been set to one of the below values:! Contact: a depositional or intrusive contact (including unconformable contacts)! Ucontact: a uncertain or speculative depositional or intrusive contact! Fault: a faulted contact! Ufault: an uncertain or speculative faulted contact! Projected: an approximate contact projected under a cover sequence as in the case of Precambrian contacts projected under a Pre-Cretaceous unconformity. Uncertain contacts should use a dashed pattern for the line type, whereas certain contacts are continuous. Faulted contacts use a heavier line weight than depositional or intrusive contacts. Create the network topology through the Map > Topology > Create menu sequence. Turn off all of the layers except the contacts layers (contact, uncertain-contact, fault-contact, and uncertain-fault) before trying to create the topology. Name the network topology xx_contacts where xx is the abbreviation for your quadrangle. After creating the network topology make sure that each contact polyline item has the xx_contacts data table attached to it, and that the object table has been labeled with appropriate values. To export the geological contact information to ArcGIS, activate the menu command Map > Tools > Export, as in Figure 7. Use the file name Contacts for the exported shape file. Select the OK button to continue. The export selection tab window will be activated at this time. Set the dialog as depicted in Figure 8. Note the options tab settings in the Figure 9 dialog- the LineCode object table is mapped to the contacts topology. This means that ArcGIS will be able to manipulate the properties of the contacts based on the type of contact. For example, a heavy line weight will be set for a faulted contact. The Figure 10 image displays the appearance of the example Page 3 of 8
quadrangle after the geological contacts have been imported into the ArcGIS project window. Note the dashed line type used for uncertain contacts. You can set the line properties through the legend editor by right-clicking on the theme name, selecting properties, and then selecting the symbology tab in the dialog. Change the legend type to Categories, add all of the data types, and then double-clicking on each line type in the legend allows you to set the line properties. Step 4: Exporting Lithologic Annotation to ArcGIS Before attempting to export lithologic text annotation to ArcGIS from AutoCAD, make sure that all lithologic annotation is in a single layer. For this example we will assume all text is in a layer named Lithology. To start the export operation select the Map > Tools > Export option. In this example the file LithologyAnno.shp was used. After this dialog, the dialog in Figure 11 is activated for selecting the text entities. In this dialog the text items in the layer Lithology have been automatically selected with a layer filter set to Lithology before clicking on the OK button. The next step is to load the text coverage into ArcMap. Starting with the ArcGIS project file loaded, check to make sure that the reference scale is properly set. Do this by right-clicking on the map. Select the Properties option and then the General tab. Make sure that units and reference scale are set as depicted in Figure 12. In addition, set the view scale to 1:24,000 by typing in 24000" into the scale box on the main menu bar (immediately right of the add data button). This sets the data view scale to 1:24,000 so that the text size is consistent. Next select the add data button. Add the LithologyAnno shape file that was created by AutoCAD Map into the project. Right-click on the LithologyAnno layer name and then select properties, and then select the Labels tab. This will generate the Figure 13 dialog. As indicated, check the Label features in this layer button to activate labels. Next, select the symbol button to set the font style and size. You can also control the color from this dialog shown in Figure 14. After setting the label size and font, select the Label Placement Options button to control how the labels are placed on the map. Set to on top of point as indicated in Figure 15. At this point you can select the Symbology tab and set the color of the text point to no color to make it disappear. Step 5: Exporting Contact Line Work Symbols to ArcGIS Line work symbology consists of special symbols that give special meaning to geological contacts. For example, teeth symbols on a thrust fault, or hachures on an unconformity contact. These features are as straightforward to export as any linework unless the AutoCAD Map file uses solids to form the block that makes up the symbol. The classic example are the teeth on the thrust fault boundary. In this case you should follow the below steps: Isolate the line work into a separate file using the AutoCAD wblock command Explode all the blocks composing the line work symbols into their component parts Export the entities to an ESRI shape file as a polygon theme Page 4 of 8
Note that the AutoCAD blocks that are the symbols must have the solids outlines with a polyline. When the polyline is exported to a shape file the closed polyline can be filled. The solids are ignored by the export procedure. When the theme is opened in ArcGIS the legend editor can be used to control the fill color. Because of this requirement you should make sure that the treat closed polylines as polgons option is on in the options tab of the export dialog. Figure 16 displays the proper setting for exporting the fault teeth line work on the Cheaha Mt. Quadrangle. The procedure for exporting structural geology data is essentially the same as for the line work symbology. The below section discusses the steps in detail. Step 6: Exporting Geological Structure Data to ArcGIS Geological structure data consists of the measurements upon which the geological map is constructed. It is necessary to display this data along with the geological map so that the user has some sense of how precisely the position of contacts are known. The first step in exporting the structure data from AutoCAD to ArcGIS is to isolate the data into a file by itself. Another key aspect is that dip/plunge amounts should be inserted as raw text rather than attributes. This is because the blocks that make the structure symbol will have to be exploded into component parts. If the dip/plunge is an attribute the original value will simply turn into the tag name (i.e. 45" will turn into Dip ). You should run MAPPRO at this time to create an AutoCAD file of structure data. S0 data from the Cheaha Mt. quadrangle will be used in this example. If you didn t save the report files generated by Access, you will need to recreate them at this time. When running MAPPRO, be sure that you indicate that dip/plunge information will be inserted as text rather than attributes (look for the checkbox under the script file setup dialog) (see Figure 17). When you have finished creating the S0 file in AutoCAD using the script command, then use the explode command and the object selection mode all to explode all of the blocks. You will now see the Dip attribute superimposed on the dip text value. Use the filter command with an attribute filter to select and then erase all of the dip attributes. Your file is now ready for exporting. Select the menu sequence Map > Tools > Export and set the export type to ESRI shape. Export the S0 data as a line topology as indicated in Figure 18. This will export only the portion of the S0 symbol that is linework. Using the same procedures to export the S0 data as a text topology. Add the themes to your ArcGIS project and then adjust the legend as depicted in Figure 19. Note the added S0" and S0anno themes that contain the linework and text labels respectively. Continue to try Access queries on all of the structure data possibilities (see AP!, AP3, F1, etc. block names in the Geologic Standards document). If you run the MapproStructureQuery on Page 5 of 8
F1, for example, and the query is blank that means that the quadrangle does not have any of that specific data. You should proceed to the next type of structure data. Step 7: Adding a DEM file A digital elevation model (DEM) is simply an array of information. The DEM depicts a threedimensional topographic surface with an array of x, y, and z values where the x and y coordinates describe the location of a node point, and the z value describes the elevation at that point. DEM arrays are also termed grids because they can be visualized as a graph paper grid that overlays the area of interest. The DEM s constructed by the USGS are designed to have grid nodes spaced at 30 meter intervals that overlay a specific quadrangle. It is important to understand that because the grid nodes are spaced at even 30 meter intervals the grid does not perfectly overlay a quadrangle. Grid nodes that fall outside the quadrangle boundary are given a no data value. Another issue that is important to understand is that the USGS has not been perfectly consistent in the way the DEM data has been presented. For example, some DEM s have elevations in feet unites whereas others are in meters. Some even have decimeter elevations. Also, the format of the grided data has changed several times so that a particular GIS application such as ArcGIS may import some DEM s but not others. In the following example the DEM for the Cheaha Mountain, Alabama, 7.5 minute quadrangle will be downloaded. Substitute your specific quadrangle name as you follow the steps. Open your favorite web browser and navigate to the web site indicated in Figure 20. Click on the state where your quadrangle is located. The next screen page presented will contain a list of counties for the selected state. Click on the name of the appropriate county. You will now see a screen similar to the image in Figure 21. You will see many different types of data listed select the 1:24,000 DEM link for this example. This selection will generate yet another web page that lists the counties in the selected state. Choose the appropriate county by clicking on the link, and that should bring up the web page in Figure 22. This web page displays the names of the various 1:24,000 USGS quadrangles that cover the county selected in the previous step. In this example the Cheaha Mt. quadrangle is selected by clicking on the green down arrow icon (i.e. the slow download speed). The next web page generated by the selection is displayed in Figure 23. In this web page look for the link that is a file name ending in zip or gz. This file is a compressed file for minimizing download time. Click on this link and indicate to your browser that you wish to save the file to disk, and then where you want to store the compressed file. You will probably want to create a folder to hold the download file before you actually download it. In this example the file will be saved to e:\usgs_dem\cheahamt. Figure 24 displays the file save dialog generated by the web browser when the save to disk option is indicated. The next step involves uncompressing the zip file, and then testing to see if ArcGIS can directly digest the DEM file. You will need the utility WinZIP to uncompress this zip file. You can find a free download of WinZip by searching for WinZip with a web browser. Doubleclick on the downloaded zip file from within file explorer after you are sure that WinZip is Page 6 of 8
installed. You should see a window similar to Figure 25. Click on the extract icon on the button bar, and point the extract process to the \USGS_DEM\CheahaMt folder. You should now verify that many files ending with DDF extension exist in the target directory. The next step is to start Surfer and load the SDTS file and then export the grid as an ASCII (ASC) format grid, which ArcGIS can import. Start Surfer and select the Map > Shaded Relief Map menu sequence. You will then see a file open dialog. In this dialog select the SDTS DEM data type as displayed in Figure 26. Select the first file name in the list and then click the OK button to load the file. You should then see the shaded relief map appear in the main Surfer plot window. If you receive an error message at this point seek help from your instructor. The next step will export the SDTS DEM grid to an ASCII grid format (GRD). In surfer select the menu sequence Grid > Extract. You will initially see a file open dialog. Indicate the name of the first SDTS file, which will be the default anyway. The next dialog window will appear as in Figure 27. Note that the file type has been set to ASCII GRD file format. You can set this by clicking on the yellow file folder icon in the dialog. Click OK to extract the grid data to the GRD file format. This new file contains all of the z, y, and z values in ASCII format, but not exactly in the needed format for ArcGIS. A utility program exists that will convert from the GRD format to the ASC format. This utility is named GRS2ASC, and it is a DOS command line program. First make sure that it exists on your system. Open a DOS window (use the start menu) and type GRD2ASC, and then hit the <enter> key. You should see instructions on how to use the program. If you receive the message bad command or file name, the program needs to be copied to the Windows folder. Seek help from your instructor if this is the case. To run the utility activate the DOS window and navigate to the directory containing the GRD file, in this case e:\usgs_dem\cheahamt (use the CD command in DOS). Type the following command: grd2asc cm_dem.grd cm_dem.asc <enter> This will proceed to convert the GRD file to ASC format. Close the DOS window with the EXIT command. You are now ready to import the grid data into ArcGIS. Start ArcMap and load the project file. Now start the ArcToolbox application and choose the ASCII to raster conversion option under Conversion Tools > To Raster. Fill in the dialog as indicated in Figure 28. The ASCII to Raster toolbox utility will add the DEM automatically to the ArcMap project. The project should appear something like Figure 29. Note that the lithologic color fills in the legend theme has been turned off in this example. Step 8: Using the DEM with Spatial Analyst Within ArcMap activate the Spatial Analyst toolbar by right-clicking on the gray portion of the toolbar. From the Spatial Analyst toolbar select Surface Analysis > Hillshade. The dialog activated by this selection should be filled in as in Figure 30. Selecting OK will compute the Page 7 of 8
hillshade and automatically add it to the project, resulting in a map appearance similar to Figure 31. You can now use the DEM data in a number of ways. Turn on the Lithologic theme and rightclick on the name. Select Properties and then the Display tab. Change the transparency value from 0% to 50%. You should now have a map that appears similar to Figure 32. At this point you have completed the steps to designing an ArcGIS geologic map. The final step prepares the map for hard copy output. Step 9: Producing a Hard Copy Map ArcGIS produces hard copy output via a Layout, therefore, you must create a layout before you can send the map to a printer/plotter. Before you create a layout make sure that you have access to the intended output device. While the project is loaded in ArcMap use the menu sequence File > Page Setup. Set the dialog as in Figure 33. Next, choose the main menu sequence View > Layout to change to layout mode. In this mode ArcMap will display not only the project map but also a virtual image of the media boundaries (i.e. the edges of the Arch E sheet of paper). Right-click on the map, select properties, and then from the Data Frame tab make sure that the fixed scale is set to 1:24,000. Because of the change in scale you may have to make the data frame somewhat larger within the layout view. See Figure 34 for an example of how your layout should appear. To send your map to the plotter select File > Print and select OK to queue the plot to the plotter. You can use the properties button in this dialog to set the plotter device driver settings. Congratulations, you are finished! Page 8 of 8