carlosh Posted October 29, 2008 Share Posted October 29, 2008 While I'm not a beginner, I find myself at a loss when it comes to creating a map on AutoCad. Currently, I'm using 2007. Here's my situation: I want to create a map with latitude and longitude lines. The problems start with the fact that the distances for coordinates X and Y are not equal. Besides, the coordinate system has to be in degrees and minutes.decimal. I have the gps coordinates for many points and locations that I need to enter. The true longitudal distance between the 2 farthest points is about 80 miles and the width is about 30 miles in an area on the Texas coast. Now that you know what I'm trying to do, where can I find a tutorial online that would teach me how to set up the coordinate system for creating real scale maps? Carlos in Austin Quote Link to comment Share on other sites More sharing options...
ReMark Posted October 29, 2008 Share Posted October 29, 2008 I saw a lisp routine at the CADCorner called vpgrid.lsp that sets up a grid in a viewport with coordinates. Does that sound at all useful? Quote Link to comment Share on other sites More sharing options...
rustysilo Posted October 29, 2008 Share Posted October 29, 2008 Are the gps coords in d.m.s.? If in xyz format you might look at this thread. Is your trouble in importing these gps points or in the setup of your dwg? Quote Link to comment Share on other sites More sharing options...
carlosh Posted October 30, 2008 Author Share Posted October 30, 2008 RustySilo: My question is directect more at the setup. As for entering locations, the default output from my GPS is Deg Min.decimal (26º41.568' 97º19.02), though I could change the output of my GPS to match the required input by AutoCad. Quote Link to comment Share on other sites More sharing options...
carlosh Posted October 30, 2008 Author Share Posted October 30, 2008 Has anybody tried the vpgrid.lsp that ReMark recommends? Carlos Quote Link to comment Share on other sites More sharing options...
rustysilo Posted October 30, 2008 Share Posted October 30, 2008 I haven't tried that lisp. If your gps can convert the format to full decimal that would make it easiest as I don't know of anything that can bring them in in a Deg Min.decimal format. If it can't you might be able to have Excel convert the value using a formula. Not sure. Quote Link to comment Share on other sites More sharing options...
ABuckingham Posted October 30, 2008 Share Posted October 30, 2008 You're going to need some math to do the conversions and make some decisions on how you want to project your gps data onto a plane. I recommend you read this article on map projection as a primer and then do more searching from there. http://en.wikipedia.org/wiki/Map_projection Quote Link to comment Share on other sites More sharing options...
DustinF Posted October 31, 2008 Share Posted October 31, 2008 While the maps that I often produce are in state plane or even local coordinate systems something over an area this large is going to be an issue when you think about what you might be using the drawing for later. If you plan on using an image under the ACAD file later the projection of both those entities will make a huge difference. Decimal degrees is more accurate than DMS format anyhow and in many cases coordinates are collected in UTM or state plane. It would likely be beneficial to start with a program such as ArcMap and enter the points there. Then import the dwg that you create into ACAD. This way you can choose what projection you want and more easily manipulate the area over which you wish to create the drawing. For as great as ACAD is at many things, mapping is not one of its stronger areas. Even the old version of ArcView will still import coordinates as X, Y data and you can use that to import the data to AutoCAD. Quote Link to comment Share on other sites More sharing options...
Guest dingo Posted October 31, 2008 Share Posted October 31, 2008 I beg to disagree with everyone. carlosh, do a google search for GDAY. get that download...it's free. as for convergence on the azimuth, forget about it. over 80 miles, unless you are doing geodetic work, you are waisting your time. Just set the download from your GPS as normal coord points. You will have to get the area code from your local, or any, government survey office. Quote Link to comment Share on other sites More sharing options...
carlosh Posted November 4, 2008 Author Share Posted November 4, 2008 Dingo, I downloaded the GDAY to see what it does. It seems to be some kind of conversion tool. I'm not sure how that helps me, but I'm going to read the user's manual. I'll report back later and let everyone know what I find. Carlos Quote Link to comment Share on other sites More sharing options...
carlosh Posted November 4, 2008 Author Share Posted November 4, 2008 I guess that this GDAY program is a bit beyond my understanding. Let me put it this way, I have many coordinates for points I've gathered. Why do I need GDAY? I can see where it converts from AGD to GDA. Now I really feel stupid. Why is GDA good for me? Does it have anything to do with AutoCad? I may be in over my head. Carlos Quote Link to comment Share on other sites More sharing options...
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