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Petri Sakkinen

DTM still unsatisfactory

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I had an opportunity to briefly test the new DTM. Looks great, with all the new functionality - but it still does not actually work, at least with larger terrain models.

This time I tried a terrain of 35,000 points (3D loci) and the results were disappointing. I was able to generate the model and even to modify settings, but there were several freezes. Slope analysis failed entirely. Well, let's say that I am not sure if it was always a freeze, since I only waited for 30 minutes or so for something to happen.

I had tried the same data set in VW 8.5.2 with no success whatsoever - but a friend of mine used AutoCAD and a 3rd party add-on (can't remember the name) on a rather old, slow PC to generate a DTM for me. It took only a few minutes and the slope analysis a couple more. The latter also had fully customisable ranges (not just even 'steps') and accepted gradients as input, in addition of awkward angles. He was able to quickly and easily switch from a rectagular grid to triangular and back again, change the size of the grid etc. No freezes, no glitches. I got both a good mesh and a rendered raster image of the terrain in less than 30 minutes.

Under the circumstances, I see little reason to get Landmark - instead, I obviously need to start to budget for a new PC and AutoCAD. The long wait was useless.

Landmark 9.0.1, 130,000K allocated Mac OS 9.1G4/400, 256MB

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Well, this is getting worse and worse.

I had another DTM to do but VW 8.5.2 gave a 'threading error.' (Like in 99% of my attempts to create DTMs.) So, back to my friends with another data set - a whopping 3,000 3D loci.

With Landmark 9.0.1, absolutely NOTHING happened. No errors, no DTM.

The point data set had even been carefully filtered not to have duplicate loci (a killer for the old DTM), but even that did not seem to help.

Back to the drawingboard, guys, before you can extract a single pound of flesh from me!

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Petri,

I'm not a DTM specialist by any means, but since Frank is at a show in Florida this week and may not see your problem, I will get the ball rolling here.

It's my understanding that our current DTM engine actually does some calculations that are dependent on all other points. So as the number of points increase, the complexity of the calculations jumps as well.

What we really need to do is actually see the data that is not working with the DTM system. That way we can try to pinpoint the cause, or point of failure. Can you email the text file with the point information to mattg@nemetschek.net? I will run it through the current development build and see if it is still broken. If it is, I will bring it the right person here and keep nagging them until it is resolved.

Matthew GiampapaTechnical Support

quote:

Originally posted by Petri Sakkinen:
Well, this is getting worse and worse.

I had another DTM to do but VW 8.5.2 gave a 'threading error.' (Like in 99% of my attempts to create DTMs.) So, back to my friends with another data set - a whopping 3,000 3D loci.

With Landmark 9.0.1, absolutely NOTHING happened. No errors, no DTM.

The point data set had even been carefully filtered not to have duplicate loci (a killer for the old DTM), but even that did not seem to help.

Back to the drawingboard, guys, before you can extract a single pound of flesh from me!

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