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dtm modeling


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i am just starting to work with the 8.5.1 version of the dtm workspace-i have both a high end g4 and a high end dell- both are giving wierd probs with the modeling

after following the tutorial- the pc seems to generate fine for some and then stall out on others and the complexity is rather low - compared to models i have done in other software

the other problem for both sides is in the rendering and closing of the sides

i am having difficulty achieving a more realistic look in mesh= and the renders on both are rather low quality if not just ugly

i apreciate any help

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I have discovered that VW's is limited however for the price it does a fair job in creating dtm's. One of it's major limitations are in the number of survey points that it can handle. I have been told that it can only manage 3000 to 4000 points which seems partly true. I have however created a model with over 38,000 points by first creating a model with a subset of the total points and then repeatedly added groups of points and used the recalculate command after each addition of points. This is very time consuming and certainly not a cost effective way of doing a dtm but it can be done. Somewhere around 38,000 points VW didn't want to work anymore. Admittedly this is a large number of points. Other programs are available that will model larger numbers of points and they do it much faster, and they cost a lot more.

I have gotten into the habit of checking only the 3d triangle view option (uncheck all other 2d & 3d options until the model is created). This seems to speed things up and has resulted in greater success for me when creating large models.

Don't pay to much attention to the progress meters if the model is large as they do not mean much. At times I have thought my computer was hung up but have found that if I wait long enough the dtm would be produced. Be patient.

As far as complexity and rendering goes I have had fairly good success with VW. Of course the greater the number of points you have the smoother the model will look if you use 3d triangles. With the mesh option the smaller the mesh the better it appears. I have used fairly small mesh openings, disregarding the "this will result in..." warning to get smooth surfaces. Be very patient if you do this as it to will take time.

I change the dtm class settings for either the DTM-triangle 3d or DTM-mesh classes, whichever is applicable, so that it has a fill color before rendering and then adjust the lighting by using the set sun position command. I would suggest using the open-gl rendering method until you are ready for a final rendering and then use the render bitmap tool and renderworks.

I'm not certain what exactly you mean by closing the sides. There is a posting dated 01-18-2000, on page 5 describing how to put sides on a dtm like the ones they show in the manual. It's rather tedious and I've had difficulty getting good results but it will work if needed.

I have used both Macs and Dell computers as well. For personal reasons I prefer the Dell but either computer should produce the same results as long as they are set up properly. The more RAM the better, on my Dell I have 320 MB but so far I haven't used more than about 140 MB (according to Norton Utilities System Info)during processing of a model. I would imagine a 1GHz machine will solve much of the time problem but a 266 MHz machine allows you to take a stretch break while the dtm is running.

Although it doesn't help right now, Diehl Graphsoft has announced that a land development program is going to be available in the future. I would hope this would include better dtm.

[This message has been edited by Marc Pitman (edited 03-30-2000).]

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