GIS Tech News (#78)

17 Mar, 2009

AutoLISP: A Civil Designer's Helpmate p>

Use this powerful programming tool to query and label GIS object data, convert unusable points, and much more.

By Salvatore Napolitano

AutoLISP can assist civil designers in many ways. If you want to push your software beyond its limits, you should consider customized programming using AutoLISP. With AutoLISP, you can make unusable survey drawings workable in AutoCAD Civil 3D. You can extract elevation data from a plain AutoCAD profile. You can also query and label object data in plain AutoCAD. I've found AutoLISP to be invaluable for doing things that supposedly can't be done with out-of-the-box AutoCAD and Civil 3D.

Make Unusable Survey Drawings Workable in Civil 3D
Nothing is more frustrating than receiving hundreds of unusable points. You select points from a survey drawing for Civil 3D surface creation. At the select points prompt, Civil 3D will respond at the command line, "0 found"! The problem: The existing conditions plan has spot elevation points as custom blocks with attributes (case 1). The custom blocks are totally useless in Civil 3D. Without an existing surface, we can't do any of our proposed grading work.

I found AutoLISP to be a quick solution to this problem. The AutoLISP program I wrote prompts the user to select the blocks, and it will create AutoCAD points at the elevation given by the elevation attribute. Then one just needs to use Civil 3D to create Civil 3D points from the AutoCAD points. An alternate solution is to use attribute extraction to output elevation data as a text file. Then you simply import the point data from the text file to create Civil 3D points. Read more »

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Salvatore Napolitano, a civil designer for AECOM Water, uses Autodesk Civil software products on various water and wastewater projects worldwide. He is located in Manchester, New Hampshire, and has more than 18 years' experience in engineering using AutoCAD.    Email:


Mark Your Calendar: GIS Events

ESRI Survey and Engineering GIS Summit
July 11-14, 2009
San Diego, CA
During this four-day summit, discover how to enhance your core business practices and expand your capabilities with the technology that is shaping the future of geospatial data management and analysis. Read more

URISA 2009 Annual Conference and Exhibition
September 29 - October 2, 2009
Anaheim, California
URISA (Urban and Regional Information Systems Association) includes management and policy discussions of IT/GIS issues affecting urban and regional governments, as well as preconference workshops, and keynote and plenary addresses. Read more

Cadalyst's complete list of upcoming events is always available on our Web site. Our sister Web site,, also offers a full calendar of GIS-related events.


What's New at

CAD Manager Survey Update, Part 2

Even when business is bad, take a proactive approach to make sure you're using your staffing and resources to their maximum potential. Read more

Data-Exchange Tools Can Save Time, Money, and Headache

Understand why you need a multi-CAD interoperability solution and how to select the right one for your office. Read more

Looking for "Hot Tip Harry?"

Hot Tip Harry's latest AutoCAD customization tips are now posted online at Cadalyst's CAD Tips site. Harry's posting tips all the time now, and you can find the latest ones by checking the Recently Posted list, along with the latest tips from Tips & Tools Weekly. You can also find out about the latest tips from Harry himself (aka Cadalyst's Bill Kramer) by hanging out on Harry's Tip Jar Discussion Forum. Look for the posts labeled "Hot Tips!" for regular updates.

Brand new, Cadalyst and Hot Tip Harry also introduce his new Programming Concepts Discussion Forum. Keep tabs and chime in to exchange AutoCAD programming expertise and advice.