GY461 Computer Mapping & GIS TechnologyDigitizing Station Data and Building a Geological StructureDatabasePage 1 of 38IntroductionThis document describes the process of converting geological data collected in the field into adigital database that can be used with a GIS to automatically post the station and structure symbolson a digital map with correct orientation, and with dip/plunge values automatically labeled. In thisprocess a relational database is created that is composed of two separate but related databasefiles:! A database containing attributes that occur once per station, such as latitude or longitude! A database containing attributes that may occur multiple times at a station point, such asbedding, mineral lineation, etc.In the following examples several types of application software are used, including database andGIS software. The examples are specific to the applications used, however, the logical stepswould be the same regardless of the specific application programs. To follow these examples youwould need access to the following applications:! AutoCAD Map 3.x or higher! Paradox 5.0 or higher! Mappro (Freeware)! Netprog (Freeware)Make sure that these applications are installed and accessible before starting the below examples.When you have completed the steps outlined below you will have created a flexible database ofstructure data that is usable with a variety of applications, including GIS. With the GIS you will beable to automatically post the structure data on a digital base map, or select subsets of the data toplot on a stereographic net.Step 1: Setup for DigitizingTransfer all station locations to a single quadrangle, preferably one that has been laminated.Inspect the stations to make sure that none of the labels are repeated. At this time you may alsowant to re-copy the structure orientation data from the field notebook into a tabular format to facilitate data entry. Tape the map onto the digitizer so that it is smooth and stable.Step 2: Insert Station BlocksGY461 Computer Mapping & GIS TechnologyDigitizing Station Data and Building a Geological StructureDatabasePage 2 of 38A block with an attribute must be designed before it can be inserted to mark station locations.Figure 1 is an example of a simple block and attribute combination. The “cross” is simply twolines, whereas the attribute is the text element created with the “DDATTDEF” command. Figure 2displays the dialog activated by this command, and the information entered to create the attribute.The center of the cross is at coordinates (0,0) because this will be the default insertion point whenthe block is inserted into another file. At this point you should calibrate your map to the UTM grid system, and identify this system foryour quadrangle. If you have already digitized portions of the quadrangle, be sure to load it firstbefore using the “TABLET” command to calibrate. Assuming that the map is loaded andcalibrated, activate the menu sequence “Map > Map Tools > Assign Global Coordinate System”.For this example we will assume that the base map is from northern New Mexico and conforms tothe NAD27 datum. Figure 3 displays the dialog activated by the menu choice with appropriateparameters selected from the drop-down list options.You should now begin to insert the station blocks at the appropriate positions on the map with thedigitizer. Position the crosshair of the digitizer puck on the first station. At the AutoCAD commandprompt type the “DDINSERT” command (or select it from the INSERT menu). This actionactivates the Figure 4 dialog. Select the “File” button and traverse the directory structure until thestation block that you have designed can be selected. At this point the dialog should appear as inFigure 4. Finish the command as indicated below:Insertion point: X scale factor <1> / Corner / XYZ: 50 <CR>Y scale factor (default=X): <CR>Rotation angle <E>: <CR>Enter attribute values Station: <Unlabeled>: CA-078Note that the “<CR>” indicates that the “ENTER” key was pressed. The X and Y scale factor forthe block was set to 50, and rotation was 0 degrees. The station label was entered as “CA-078".Continue this procedure until all station data is completely marked by blocks. At this point, theexample station map would appear as in Figure 5.Step 3: Extract the Station Data Locations in a Database CompatibleFormatIn this step the “DDATTEXT” command will be used to extract the station location data in aformat that can be imported into a database or spreadsheet application. For this example we willGY461 Computer Mapping & GIS TechnologyDigitizing Station Data and Building a Geological StructureDatabasePage 3 of 38use Paradox 5.0 because we will eventually add the structure data within that application system.We should store the station locations in the most flexible format possible, i.e. latitude andlongitude, therefore we will use the map projection capabilities of ACAD Map to create a mapbased on latitude and longitude coordinates. Start ACAD Map, create a new drawing, and assignto it a latitude-longitude coordinate system. Figure 6 displays the appearance of the dialog once thecoordinate system has been chosen. In this case NAD27 latitude and longitude coordinates indegrees were picked. The next step creates a file “query” that imports data from the original UTM coordinate file. Figure7 displays the dialog activated by the “Map > Drawings > Define or Modify Drawing Set”. Usethe “Attach” button in the dialog to find the original UTM base map and then select the “OK”button. The Dialog should then appear as in Figure 7. Immediately select the menu combination“Map > Query > Define Query”, which activates the Figure 8 dialog. Select the “Location” buttonand then indicate “All” to query all items in the file. Then change the query mode to “draw”, andthen execute the query by selecting the “Proceed” button. You should then see in the drawingwindow the same map as you did with the original UTM map, but note that now the coordinatereadout will indicate latitude and longitude degrees. Also note that longitude is negative, as itshould be in the Western Hemisphere.Now we are ready to extract the attribute data. This is done with the “DDATTEXT” command,which is the dialog for attribute extraction. Figure 9 displays the dialog activated by this commandwith relevant data typed into the edit fields. Note that the station blocks were picked with