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Surveying GIS

April 1, 2004
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An exercise with Autodesk Map.

The seamless marriage of CAD and GIS has been referred to as the "Holy Grail." Last December my personal "Quest for the Grail" led me to an unlikely place, geographically speaking: Las Vegas. It was there that Autodesk University was once again held at the MGM Grand. The first thing that stood out to me was that the attendance was noticeably greater than in 2002 at the same venue-some 30 percent more. So I naturally looked for facts to support my observations. The number and content of the sessions was similar-or so it seemed. So that wasn't it. The core attendees I met last year were there. The usual array of vendors with the "latest and greatest" third-party offerings filled the exhibit hall.

Most of the sessions were set in convention center classrooms and included PowerPoint presentations. There were also quite a few "labs" available. Several were GIS-oriented. A GIS-oriented GPS lab titled "Hands-On GPS and GIS" was standing room only, and it was about the only place the word "surveyor" was mentioned. It was obvious to me that Autodesk aimed its message primarily at engineers and designers.

It seems the good folks at Autodesk have apparently figured out that the majority of the people who are in the business of actually creating spatial data through the process of collection primarily work in the CAD platform. Eureka! And inspired by this revelation, there was a new enthusiasm for promoting the GIS and mapping sectors of the CAD empire.

The course speakers seemed to restrain themselves and made references to, but did not utter the "four letter word" or its allies. But when we got to the part about Platform Independent Spatial Data "our friends at ESRI and Intergraph" repeatedly made their way into the conversation. There was a lot of support for the idea of the Open GIS Consortium.

This, in fact, is precisely the reason I have been attending Autodesk University for the past few years. In my past articles I have explored the various ways to introduce CAD drawing files into GIS projects. This time I will take a look at the reverse side of the coin. We will take some ESRI Shape files, attach them to an Autodesk Map project, and query the data.

I once cautioned experienced CAD users venturing into GIS products that they would likely find the CAD capabilities of pure GIS products frustrating, at least in the beginning. It is probably also fair to point out that those familiar with pure GIS products may find Autodesk Map not as well suited to some of their particular needs. With that in mind, let us proceed to a sample exercise.

Fig 1: Autodesk Map view with utility pull-down.

Sample Exercise*

Let's suppose I have a boundary and topo project. I have been provided with a CAD drawing of some aerial topo. And I also have some GIS data in Shape file format with boundary and control base map data. (And as luck would have it it is all on the same coordinate system.) I want to work in CAD, but I also want to make use of the GIS data without any additional software. Can I do it? Sure.

First, I open the topo drawing in Autodesk Map. In the view I see the Map menu pulled down to the "Utilities" option. The window on the left of the screen is called the "Project Workspace." It can be toggled on and off by checking it here.

Now, from the Map pull-down menu, I select "Tools" and then "Import." In the "Import" box I arrow down to "ESRI Shape" and navigate to the folder where the Shape files reside. I then click "OK." In the "Import" dialog, I check the boxes of the Shape files I wish to import. Then in the "Data" field, I click the ellipses and choose "Create from Attribute Data." This action produces a box displaying the message "Processing entities."

Fig 2: In the "Import" box, arrow down to "ESRI Shape" to get to the Shape files.
By zooming out I can view the entities imported from the Shape files. So where is the Attribute data? I haven't attached it yet. This is where the Project Workspace comes into play. If I toggled it off, I would need to restore it.

Fig 3: By zooming out you can view the entities imported from the Shape files.
Next, I use "Save As" to save the project drawing containing the imported Shape file data with a different name. Then I reopen Map. In the Project Workspace window, I right click on "Drawings," choose "Attach" and select the drawing I just saved. Then I right click on the drawing and choose "Zoom Extents" and "Quick View."

Fig 4: View of field in attached table.
In the Project Workspace, I right click on "Data Sources." (Right clicking activates or executes nearly everything in Project Workspace.) I then choose "Configure." In the Data Source box I enter the name of my database (in this example I use the name of the folder the Shape files reside in). I click "OK" and the Data Link Properties dialog is displayed. I click the "Test Connection" button, which should then read "Test Connection Succeeded."

Fig 5: In the Project Workspace, select "Define Link Template," and a "Key Field." Under Link Templates, click on a link and choose "Generate Links," then "Create Data Base Links" radio button and "OK."
I then right click on "Data Sources" again and this time choose "Attach." The name of the folder I used should appear with a .udl (Universal Data Link) extension. The ESRI Shape file tables are .dbf. I arrow down and select .dbf. If this step fails, I may need to go back to the Data Link Properties dialog and select "dBASE" files from the pull-down menu.

I click "OK" and the names of the tables in my Shape files should appear in the Project Workspace. I can now view the data in the tables. I right click on a table and choose "View table." All the attributes will be displayed. To make the attributes more useful there is one more step: linking the table to the drawing.

I right click on a table in the Project Workspace and select "Define Link Template." I then select a "Key Field." (It is best to choose a field that contains a unique identifier.) Under Link Templates, I click on a link and choose "Generate Links." I then choose the "Create Data Base Links" radio button and click "OK."

Fig 6: In the Query Library, right click on "Current Query" and choose "Define." This brings up the Query Dialog.
To use this linked data I need to develop a query. In Autodesk Map, Query has a much broader connotation than it does in other GIS and database products. The Query is basically the GIS "˜engine' for Autodesk Map. In the Query Library, I right click on "Current Query" and then choose "Define." This brings up the Query Dialog. The Query Dialog contains all the controls for the Autodesk Map GIS "˜engine.'

The first thing I need to do is locate the area I am interested in viewing. With the "And" and "Draw" radio buttons set, I click the "Location" button. This brings up the Location Condition box. I will choose "Circle" and "Crossing," then click "Define." Map prompts me to draw a circle. I set the radio button to "Draw" and click "Execute Query." The Command line will display a value indicating the number of objects queried.

OK! I am now ready for the GIS part. I right click "Define" again and this time choose "Data." This brings up the Data Condition dialog. The "Object Data" radio button should be checked. The fields from the .dbf in the Shape file will be displayed in the Object Data Fields box. I choose the fields I wish to query (one at a time) and click "OK" after each.

I now activate the "Report" radio button and click "Options." This brings up the Output File Options dialog. I assign a .txt output file name and location, and click the "Data" button. I choose the fields I wish to display in the report and click "OK" and then "Execute Query." I can now open the text file and view the result.

Finding the Holy Grail

Oh, and about that Holy Grail. For the grand finale of Autodesk University 2003, the hosts closed with a special showing of "Monty Python and the Holy Grail" with special guest, actor John Cleese. It seems fair to conclude that Autodesk was making a bold statement about the future.

*Note: the exercise in this piece utilizes Autodesk Map 2002. The user may observe somewhat different results than those shown here. Map 2004 has Safe Software FME (Feature Manipulation Engine) embedded in the coordinate and file translation routines, greatly improving proficiencies in those areas.

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