AutoCAD 1:24,000 Geologic Map Standards

Transcription

1 Introduction This document describes the process of adding geologic information to a digital quadrangle base map with AutoCAD Map 2000i. It is assumed that this digital base map has been constructed according to the guidelines in a companion document that outlines digitizing 1:24,000 USGS topographic information. AutoCAD Map is a fullfeatured GIS system, and is fully capable of producing the highest quality geologic map and cross-sections. Below are several general notes about the setup for creating the geologic map. At this time start AutoCAD Map, and then load the quadrangle base map through the File º Open menu. Immediately select the menu sequence File º Save As to save the file with a new name that reflects the fact that this file will be a geologic map. Below is a list of various layers and layer settings that are typically required for geologic maps. Your specific map may or may not require all of these layers. The brief statement under the Comment heading describes the items stored in the layer. Some of the layers such as border are repeated from the 1:24,000 quadrangle standards document. Layers (see 1:24,000 quadrangle standards for other) Name Color Line Type Comment AP1 Black(7) Continuous 1st gen. fold axial plane AP3 Black(7) Continuous 3rd gen fold axial plane Base Black(7) Continuous miscellaneous objects/text Bedding Black(7) Continuous Bedding orientation data Border Black(7) Continuous Quadrangle boundary C1 Black(7) Continuous 1 st generation crenulations C3 Black(7) Continuous 3 rd generation crenulations Contact Black(7) Continuous Geological contact DRG Black(7) Continuous USGS Digital raster graphic AAprime Black(7) Continuous Cross section line A-A F 1 Black(7) Continuous 1st gen. fold hinge F 3 Black(7) Continuous 3rd gen. fold hinge Fault-contact 12 Continuous Fault contact FaultLineWork 12 Continuous Fault contact linework L 1 Black(7) Continuous 1st generation mineral lin. Lithology Black(7) Continuous Lithologic codes text LithologicPolygons Black(7) Continuous lithologic polygon fills LithologicCentroids Yellow Continuous lithologic centroid points Pegmatite Red(1) Continuous 30 m wide Page 1 of 31

2 Raster Black(7) Continuous Scanned field map Rivers-Lakes Blue(5) Continuous River and lake areas S 0 Black(7) Continuous Compositional layering S 1 Black(7) Continuous 1st generation foliation Stations Black(7) Continuous Station location markers Structure 12 Continuous Special megascopic structure symbols (axial trace, etc.) Uncertain-Contact Black(7) Dashed2 Uncertain geological contacts Uncertain-Fault 12 Dashed Dashed fault contact Uncertain-Structure 12 Continuous Speculative structures UnconformityLineWork Black(7) Continuous unconformity linework Note that the above layer names in italics are the names of structure data types that are posted into the map by the utility program Mappro. You can use the internal AutoLISP or stand-alone version of Mappro to post the structure data. Below is a list of blocks commonly used with geologic maps. Most of these blocks are structure symbols that are automatically inserted with the application MAPPRO. For more information see the companion document regarding the posting of structure data from a database. Other blocks, such as Teethbk designate fault line work symbols. Blocks (*always insert in layer of same name except where noted) Name Scale Comment Bed 200 Bedding symbol S Compositional layering or bedding {planar} S st generation foliation {planar} L st generation mineral lineation {linear} F st generation mesoscopic fold axes {linear} F rd generation mesoscopic fold axes {linear} F th generation mesoscopic fold axes {linear} C D 3 generation crenulations {linear} AP F 1 axial surface {planar} AP F 3 axial surface {planar} AP F 4 axial surface {planar} JT 200 Joint surface {planar} DownBk 200 Down-thrown side of normal fault ball-and-stick markers (spacing=500m); layer FaultLineWork St 50 Station marker block; layer stations Teethbk 100 Thrust fault hanging wall markers(spacing=500m); layer FaultLineWork Page 2 of 31

3 Fhach 70 Normal fault hanging wall hachures(spacing=500m); layer FaultLineWork Uhach 35 Unconformity hachures (spacing=50m); layer UnconformityLineWork The lithology style controls the size of the geologic unit labels. You do not add these labels manually. A procedure will be demonstrated that adds these labels to each lithologic polygon automatically. Note that the template file Map_Prototype.dwt can be utilized to automatically insert all block symbols commonly used to construct geologic maps. Using a template will be demonstrated in class. Styles (see 1:24,000 quadrangle standards for others) Name Font Height Comment Lithology Arial 100 lithologic nomenclature code text Create Contact Symbols Step 1. Prepare Geological Contact Linework Before attempting to add the linework symbols for fault contacts or unconformable contacts you should first check to make sure all geological contacts are in the correct layers: Contact : regular depositional and intrusive geological contacts Uncertain-contact: speculative contacts (dashed) Fault-contact: faulted contacts (heavy line weight) Uncertain-fault: speculative fault contacts (heavy wt., dashed) The symbols that are added to faults and unconformities vary a lot so you should consult the list of block symbols above to match up with fault types. For example, the block Teethbk is used to insert the teeth marks on a thrust fault. When checking your linework it is particularly important that the transition from a regular contact to an uncertain contact be gap free. In other words the ending vertex of the regular contact must be snapped to the beginning vertex of the uncertain contact. An easy way to do this is to change the line type of the layer Uncertain-contact to continuous, and then make the layer a color that contrasts well with the other elements of the map (I recommend magenta). If you zoom to the drawing it will then be easy to detect any gaps and fix them using object endpoint snap editing. Page 3 of 31

4 Step 2. Insert Block Symbols For this example thrust fault symbols will be inserted along a thrust fault contact on the example Cheaha Mt. Quadrangle. Make layer 0" the current layer after the map is loaded. Zoom in to a small area off to the side of the quadrangle itself. Note that in the block name list above the block Teethbk is to be inserted with a scale factor of 100. From the main menu select Insert º Block. From the Insert dialog window select the Browse button. Use the file open dialog to find Teethbk.dwg in the \AcadmapData\Blocks subdirectory. Set the insert dialog as displayed in Figure 1. Note that the scale and rotation are preset but the insertion point is not preset so that the block can be placed with the pointing device. The block should be exploded to avoid nested blocks. Step 3. Make Right- and Left-handed Copies of the Block You will need right- and left-handed copies of the block so that any specific side of a contact may have the symbols inserted on it. Use the copy command to map a copy of the inserted block and place it just to the right of the original. Use the rotate command to rotate the copy 180 degrees. Keep in mind that when using the copy and rotate command that the block may be made up of more than one elements so use a selection window to make sure you get all of the original block. Now use the block command to turn the left symbol into a block named Teethbk1" and the right symbol Teethbk2". It is important to use a midpoint snap mode to exactly snap to the midpoint of the base of the triangular block. The dialog in Figure 2 displays the Block command settings. Step 4. Use the Measure Command to Insert Symbols Along Contact The measure command can insert a block tangent to a polyline at a specified intervalexactly what we need to mark the thrust fault contact with teeth symbols. Zoom window to a fault contact that you wish to add symbols to. Make sure the current layer is set to FaultLineWork. Type measure and the command prompt and then hit <enter>. Indicate the following answers to the ensuing prompts: select object: (select the desired fault contact with a left-click) specify length of segment or [block]: B <enter> enter name of block to insert: teethbk1 <enter> align object with block [Yes/No]: Y <enter> specify length of segment: 500 <enter> The block symbols will then be inserted at 500 meter intervals along the contact. If the symbols appear on the wrong side of the contact, immediately use the undo command to Page 4 of 31

5 erase the symbols. Then run the measure command as before but use the other block (teethbk2). Figure 3 displays the results of using the measure command on fault contacts in the NE portion of the Cheaha Mt. Quadrangle. Creation of Lithologic Polygon Coverage with AutoCAD MAP Step I. Define Polygon Boundaries A) Turn on only those layers that define the boundaries of the lithologic polygon. Usually this will consist of the layers: Border Contact Fault-Contact Uncertain-Contact Uncertain-Fault Rivers-Lakes All of the boundaries that you see on the screen should visually define geometric polygons. Unfortunately faults may die-out along their trend leaving a contact hanging with no polygon closure. In this case the fault contact must be moved to a separate layer that should now be turned off. B) Double check that all layers that do not define lithologic polygon boundaries are turned off or are frozen. C) If a query is used to import polygon boundaries to the current drawing, make a decision at this time as to whether or not these entities should be saved back to the original file. If you do not want to alter the original drawings (most common situation), detach them from the current session. Step II. Clean the Polygon Boundaries A) This step cleans any incorrect polygon topology from the current drawing. Select MAP º MAP TOOLS º DRAWING CLEANUP from the MAP menu item. Figures 4 through 6 document the sequence of selections to be made in this dialog box. In Figure 4 you should manually select all of the objects that will be polygon boundaries on the geologic map. All other layers should be off at this time. Select the Next button to move to the Figure 5 step in the dialog. Select the indicated options in the Selected Actions list box. You should not have the simplify objects or snap clustered nodes chosen at this point. Again select next to move to the next step. In Figure 6 you should select the Modify original objects button. This means that the original objects (polylines) will be modified. Select the Finish button to complete the process. You should note that now all intersecting polylines have been broken into separate polylines in the layers that will be part of the Page 5 of 31

6 polygon topology. Step III. Create Polygon Topology Important Note: There is a glitch in the 2002 version of AutoCAD Map that causes problems in this step if you have symbols in the FaultLineWork or UnconformityLineWork layers. The blocks in these layers are treated as unattached points and are marked as errors (many red rectangles). If you are using the 2002 version, work around this glitch by simply Freezing the FaultLineWork and UnconformityLineWork layers, then follow the below steps to create the polygon topology, and then un-freeze the layers. Since the blocks are not part of the polygon boundaries they will not affect the creation of the topology. A) Create the layer LithologicCentroids for polygon centroid markers. These markers will be automatically inserted into the center of gravity of each polygon. Set the color of this layer to #240. B) From the MAP º TOPOLOGY º CREATE dialog create a polygon topology. Figure 7 displays the beginning step of this dialog. As indicated, indicate a name and description for this new topology. Make sure that the type of topology is set to polygon. Select the next button. Figure 8 displays the next step in the create topology dialog- selecting the links (i.e. polylines) that will form the boundaries of the polygon topology. As indicated, manually select the links by clicking on the select object button, and drawing a selection window around all of the displayed objects. Right-click the pointing device to return to the dialog. Click the next button to proceed to the next step. Figure 9 displays the next step in the create polygon topology process. Select the select objects button and draw a selection window around the entire drawing to select all nodes that exist in the polylines. When finished, right-click the pointing device to return to the dialog, and then select the next button. The next step in the dialog is the Create new nodes step. You can skip this step in the dialog by selecting the next button. Likewise, the next Select Centroids step can be skipped by selecting the next button again. Note that if you were attempting to add new polygons to an already existing polygon topology you would select any pre-existing polygon centroids in this step. The next step is the Create new centroids step that is displayed in Figure 10. As in this case, anytime you are attempting to add new polygons the create new centroids box should be checked. Note that the layer LithologicCentroids is selected so that the newly created centroid objects will be in that layer. Select the next button to proceed to the last step in the dialog. Figure 11 displays the setting for the last step in the dialog- error markers settings. Set the dialog as indicated in this figure. Select the finish button to attempt to create the polygon topology Page 6 of 31

7 At this point AutoCAD Map will usually report a number of errors by marking such errors with a triangle. The error marks are normally put in the current layer. You should now investigate and correct errors located at the center of each triangular error marker. Note that many of the markers will be centered on false errors. This is because if any intersection of polylines around the perimeter of a polygon is faulty, all intersection are marked as an error. At true errors you will usually see 2 closely spaced triangular error markers. After fixing any errors try repeating the above steps in the create topology dialog. If you continue to fail to create the polygon topology seek help from your instructor. A completed topology for the Cheaha Mt. Quadrangle is displayed in Figure 12. Note the centroids that are located near the center of each polygon. C) After processing the polygon topology, ACADMAP should report that the topology is correct and complete. You can always check this status by doing an audit with MAP º Topology º Administration º Audit. You can check the statistics of the polygon topology (number of polygons, average area, average perimeter, etc.) by selecting the MAP º TOPOLOGY º ADMINISTRATION º Statistics menu item. D) A few hints about successfully completing the polygon topology: :! The cleanup process should break polylines at all intersection, if they are not broken the polylines must not actually intersect.! Overshoots across boundaries will produce small slivers of polylines that may not be easily seen but will be marked as an error.! Before attempting to create a polygon coverage, click onto map borders and other polylines to determine if they have been broken correctly.! After correcting under- or overshoots with editing commands like extend and trim, don t forget to run through the cleanup process again before attempting to create a polygon topology.! If repeated attempts to create the polygon topology fail, run back through the cleanup process and select snap clustered nodes with the default tolerance. If this doesn t solve the problem seek help from your instructor. Step IV. Create Lithology Object Data A) Object data must be created to hold the lithologic code for each polygon. After the object is created, an instance of the object will be attached to each polygon centroid point. After this step, each object is edited by entering the lithologic code. B) The MAP º OBJECT DATA º DEFINE OBJECT DATA command should be selected Page 7 of 31

8 at this time, and then click on the New Table button. You should fill in the resulting dialog as in Figure 13. This action will create an object table named??_lithology. This table will contain one field Name Type Default value LithologicCode Character unknown C) The MAP º OBJECT º ATTACH command is then used to attach an instance of the object to the centroids. First use the filter command to build a selection set consisting of only the centroid points (Object type=point) first. When the above menu sequence gives the select objects prompt, type in prev to indicate the previous selection set. Figure 14 displays this dialog. D) The MAP º OBJECT º EDIT command is then used to enter the appropriate lithologic code for each polygon on the map. See Figure 15 for an example of the edit object data dialog. Step V. Process the Thematic Query A) A thematic query will allows one to define a table of fill colors to match specific lithologic codes. When this query is processed, fill patterns are automatically generated to fill in the lithologic polygons. This is done based on the codes entered in the above step. The fill patterns are in fact hatch patterns that are inserted in the current layer, but have a color characteristic defined by the query table value. B) Use MAP º QUERY º TOPOLOGY THEMATIC QUERY to begin the thematic query creation. The menu selection will activate the dialog displayed in Figure 16. Fill in the dialog as indicated below: Specify topology name to load:??_lithology Specify thematic expression: LithologicCode@??_Lithology Specify display property: Fill Within the Display Properties dialog, the define button is used to set up the link between fill color/pattern and a value. For example, if Quaternary terrace deposits should be filled in as a solid yellow color, then the color yellow solid pattern would be added to this definition table. The value for this entry would be Qt. See Figure 16 for an example of the dialog settings just before the proceed button is activated. Because the task of specifying the color-to-lithology mappings is tedious, your instructor may in fact give you a predefined file of settings to load. If you are given a file name, select the lower right Load... button in the Figure 16 dialog and proceed to load the thematic settings. Selecting the Define button will display the current thematic definitions such as the example in Figure 17 of the Page 8 of 31

9 default theme for geologic mapping in the Alabama Piedmont. This will be provided to you by the instructor, but remember that it had to be constructed originally from the Define button option and then saved to disk. You will have to edit the theme file slightly to match the names of the topology and object data table. This can be accomplished easily with the Notepad text editor, and will be demonstrated in class. C) When all of the fill color links are defined, select the proceed button to activate the insertion of the fill colors. Note that the fill colors, which are in fact solid hatch patterns, will be inserted into the active layer, however, the color will match that of the definition table. The fill patterns should be inserted into the LithologicPolygons layer, therefore, make sure that this is the active layer before selecting the proceed button. After processing is complete, check the drawing closely for mistakes. If you have not tagged all of the polygons with a lithologic code the corresponding polygons will not be filled. If you misspelled any of the lithologic codes, the same problem will appear. If this does happen remember that you must erase the current set of color fills before to process another thematic query. Correct any lithologic code errors, erase the current color fills, and then process the thematic query again. Another possible problem that may arise is the color filling of water bodies. The predefined thematic query may not have a fill for water, therefore, you should add a lithologic code water to the definitions with color fill of cyan. D) When the fill hatchings are inserted, they may be on top of other features such as contacts, streams, etc. To keep these features from being obscured, the fill objects should be sent to the bottom of the display order. Turn off all layers except the LithologicPolygons layer, then execute the Tools º Display order º Send to Back to rank the lithologic polygons as the first item to be drawn. Reverse this procedure to send all other layers to the top of the order with Tools º Display order º Send to Front. An example of the Cheaha Mt. Quadrangle with geologic polygons filled is displayed in Figure 18. Adding Lithologic Code Text to Centroids Step 1: Creating a Style for Lithology Labels Use the style command to create a style named Lithology with an Arial font and a text height of 100. Make the layer Lithology the current layer. From the main menu select Map º Query º Define Topology Query. In this example we will use the CM_Lithology polygon topology and the query will be temporary. Select the Define Query button. In the dialog in the Query Type section click on the data button and set the criteria to LithologicCode = *. This will cause the query to match any lithologic code text. In the define query dialog set the Query Mode section to Draw. In the Options section select alter properties. Click on the Text button and then the Data button. The field name LithologicCode will be selected by default since it is the only field name associated with the data table Cm_Lithology. Select the OK button. The dialog should appear as in Page 9 of 31

10 Figure 19. Select OK again to return to the Set Property Alterations dialog window. This dialog should appear as in Figure 20. There may be other criteria left over from other operations in the expression window- delete them at this time. Select the OK button again to return to the Define Query dialog. The window should appear as in Figure 21. Click on the Execute Query button to run the query. This should automatically label every centroid. Note that bodies of water will be labeled water - delete these labels from the drawing (hint: use the filter command to delete them all in one step). Adding Structure Data The addition of structure data is addressed in a separate document that covers the use of the Access database application for data queries. Refer to the GY461_InsertingStructure.pdf file located at: Review the placement of the structure data with your instructor before proceeding to the next step. Plotting the Map Plot the geologic map as with the same plotter setup parameters as described in the quadrangle standards document. You should turn off the lithologic centroids and stations layers before plotting. Remember that the scale is 1 plotted inch = meters (i.e. 1:24,000 scale). The map should easily fit onto Arch E size media in landscape orientation. Page 10 of 31

11 Figure 1: Block insert dialog window. Page 11 of 31

12 Figure 2: Block command dialog window. Page 12 of 31

13 Figure 3: Example of using the measure command to add thrust fault symbols to faulted contacts. Page 13 of 31

14 Figure 4: Initial drawing cleanup dialog box. Page 14 of 31

15 Figure 5: Options for processing the map cleanup process. Page 15 of 31

16 Figure 6: Finishing the map cleanup dialog. Page 16 of 31

17 Figure 7: Step 1 of the Create Topology dialog- naming the topology.. Page 17 of 31

18 Figure 8: Dialog for selecting objects from which a polygon topology will be created. Page 18 of 31

19 Figure 9: Step 3 of the create polygon topology process- selecting nodes.. Page 19 of 31

20 Figure 10: Step 6 of the create topology dialog- creating missing centroids setting. Page 20 of 31

21 Figure 11: Last step in create topology dialog- error marker settings. Page 21 of 31

22 Figure 12: Example of polygon topology centroids. Page 22 of 31

23 Figure 13: Define object data dialog example for lithologic polygon topology. Page 23 of 31

24 Figure 14: Dialog for attaching object data to polygon centroids. Page 24 of 31

25 Figure 15: Dialog initiated by the edit object data dialog. Page 25 of 31

26 Figure 16: Thematic query dialog activated from the query menu. Page 26 of 31

27 Figure 17: Thematic query definitions for geologic map that were loaded from a theme (thm) file.. Page 27 of 31

28 Figure 18: Example of color filled polygon topology. Page 28 of 31

29 Figure 19: Define text dialog for creating Lithology text labels. Page 29 of 31

30 Figure 20: Set Property Alterations dialog setup for creating Lithology text labels query. Page 30 of 31

31 Figure 21: Define Topology Query dialog window for creating Lithology text labels at every centroid. Page 31 of 31