IMAGINiT Civil Solutions Blog

Converting Map Explorer Data to GIS-Friendly Objects

Bryant Quinney | Applications Expert

When working inside of the Map 3D environment, we frequently have the need to interact with an entity specializing in GIS. Whether that group utilizes Map 3D or an ESRI-based product, we can ensure that our data resolution and relevant data make a seemingly easy transition through the use of Shapefiles.

In this example, we will work with an attached database of an appraisal district. Since the database has a single table that houses all the necessary fields, populated with data, we will not be using Object Data as this will basically double our output.

1. With the database connected, and Link Template “designed” from it (as the triangle indicates), we have established a link between our geometry and the database records using the [PROP_ID] column as a lookup.

 

Note: There is a bonus to establishing a Link Template and generating the link to a representative object, then creating an object class. That link template key shows up in the listing of properties for object classification, so it is automatically added as an entry in the properties of any new classified objects. It is a good practice that you set the default value to a number that will not be found in the database, such as 0 (zero).

2. At this point, classify your drawing geometry as you would normally. Because the object class assignment generated a place-holder for our PROP_ID value, we cut out the extra steps it would take to generate the links from the corresponding link template. Now, when you enter the value for the object(s) found in the database, the list of properties populates with those found in the table.

 

3. Using MAPEXPORT, we can export our geometry to a Shapefile, using polygons (in this example) as the object type.
4. To include the data for each object found in the database table, in the export dialog box à Data tab, click on the Select Attributes button at the top.
5. Expand Link Templates, then place a checkmark next to the name of Link Template that is used in the drawing file.

 

6. On the Options tab, for this data set, we need to place a check mark in the box for treating closed polylines as polygons so that they are properly recognized as such. Click OK to begin the export.
7. Since the data is now housed in a .SHP format, we can test out what has been exported to the file set.
8. In Map 3D, switch to the Display Manager tab on the Task Pane and click Data à Connect to Data…

6. Connect to the SHP data source that was previously created (it is okay to be in the same drawing) and add it to the drawing.
7. Inspect the new layer by looking in the table. You should see the entries for your drawing geometry in the same format they were published, according to their corresponding database

EATTEXT command to Reverse Create a Survey Point File From Blocks

Craig Batchelor | Applications Expert

I recently came across a student that received a survey AutoCAD file that contained attributed blocks inserted at elevation 0. Each instance of the blocks contained an attribute with the point's respective elevation value. Because Civil 3D does not have a direct way to utilize this type of data for surface creation, there are a few ways to achieve the desired end result.  One method would be to use the command “MOVEBLOCKSTOATTRIBELEV” to move each block to its respective Z-value, then create a surface using “Drawing Objects” and the “Blocks” option.  In this case, the student wanted an actual survey-like external ASCII file.  The solution in this case was to create a point file by extracting the coordinates Geometry for Position X and Position Y, and the Block attribute for the Elevation. This can be done with the EATTEXT command.

The EATTEXT command is an eight-page Data Extraction wizard. That allows the user to get the desired shopping list of ingredients to make the point file.

Page 1 can Create a new data extraction

Page 2 sets the Data source

Page 3 allows to select the attributed block.

Page 4 allows for a Category filter of the Attribute and Geometry. Also checking the box of the XYZ Property.

Page 5 allows to set the order of the columns by dragging them to a Northing Easting Elevation format

Page 6 Allows to set the Output data to external file (xls, csv, mdb, txt) In this case CSV is selected

Page 7 is omitted with this extraction

Page 8 Allows to select Finish.

Once created, the Header row one needs to be removed from the file, and then the point file can be inserted into Civil 3D.

The result is an external ASCII file of "survey data" that can be used to create Civil 3D points in the drawing that can then be used to create a surface.

Bathymetry on a Grid in Civil 3D

Craig Batchelor | Applications Expert

In my travels recently, I came across a student that had thousands of points of bathymetry collected by a boat. His wish list was to create a grid type surface at a designated interval and simplify the surface. We started with a file of over 10,000 points at 2-foot intervals along a path, and ended up with 1600 points in a grid pattern at 20 feet (or any other interval). The client was outsourcing the grid surface, not knowing it was simple to create in his existing software.

This is a summary of how to accomplish creating ta grid surface with Autodesk Civil 3D using bathymetry data.

After analyzing the point file, insert the file into the drawing from the INSERT tab Points from file and Insert CSV file.

Once inserted, select a point and List Available Point Numbers to find an unused group of points to create the surface grid.

In the Create Points chevron drop-down, set a point number that does not overwrite the bathymetry shots and set the Elevations and Descriptions to Automatic.

Create two new Point Groups. One for No Display and another for Bathymetry. Select the order to No Display on top.

Create a Surface named Bathymetry and add the Bathymetry point group to the definition.

Draw a rectangle around the surface with a coordinate base point in the lower left.

In the surface point creation pull-down, select On Grid.

Command: _AeccCreatePoints

Command:

• Surface: Bathymetry
• Specify a grid basepoint:
• Grid rotation <0.0000 (d)>:
• Grid X spacing <5.0000>: 20
• Grid Y spacing <20.0000>:
• Specify the upper right location for the grid:
• Change the size or rotation of the grid/grid squares [Yes/No] <No>:

Create a point group of the new points

Create a surface and add the new point group to the definition.

Set to a unique style and see the smoother surface in the comparison

Conclusion:

Collecting Bathymetry by boat tends to give an excessive amount of points in lines. By creating a grid of the surface, it will be simplified and easier to label and use in production.