DTM error message 20, 1

[Cerveza Little]

I regularly get the Miscellaneous error message (20, 1) for DTM site modelling from 3D points imported from a GPS system. Sometimes I get the contours to appear, but usually I get this error message. Sometimes I can solve the DTM by exporting to my MAC platform, but I still get the error message there as (20, 2). I am using XP, version 11.5. Are there any work-arounds for this problem?

[Guest]

Try running the check 3D polys command and filter 3d polys

The error message indicates two things:

The data is crossing at at least one place in the drawing (2 or more polygons co-exist in two x,y,z locations)

or

The data is too complex and needs to be filtered down - if the polygons have hundreds or vertex points along them, then the data can be filtered down without losing any of the model detail.

[Petri]

The data is too complex and needs to be filtered down - if the polygons have hundreds or vertex points along them, then the data can be filtered down without losing any of the model detail.

Excuse me, but this statement is totally untrue. Please explain how you can create a DTM of, say, Finland without at least hundreds of points of vertex points along hundreds of polygons "without losing any detail".

Right - you mean that the DTM is only intended to model a single house site. located in a flat area... Well, that's different!

Edited October 27, 2006 by Petri

[Cerveza Little]

I have no polygons evident, just 3D locus points that were imported from a dxf. I did get the model to give me contours, but just once, after restarting Vectorworks with only the one file present. However, that wasn't the issue, since I have tried to repeat the steps that gave me the initial model, but to no avail. There are about 2,000 points in the model. I get this message often, but not every time I run a model. It seems to be independent of the complexity of the drawing.

[Guest]

Petri,

You can model finland with polygons that have several hundred vertex points. I should have clarified the statement - excessive points along a polygon/contour line will cause an error such as what you are getting. Since the DTM is a triangulated object, removing excess vertex points does not affect the model. If the extra vertex points are filtered out too much, then yes, the model will be affected. In that case though, the removed points are not excess points.

Please keep in mind that this is a professional message board and that people genuinely want to help. However, when tone/words are not professional and courteous, it is harder to get the help one may be looking for.

Now, as to the error message, I've given you the explaination to alleviate the error message. You can choose to use the advice or not.

[Cerveza Little]

The model is contouring correctly now after creating a new drawing and pasting all of the 2000 3D locus points into the new drawing. I had been trying new drawings all day but had had no success until now. Is there any reason why a certain new drawing would work as opposed to another?

[Petri]

Please keep in mind that this is a professional message board and that people genuinely want to help. However, when tone/words are not professional and courteous, it is harder to get the help one may be looking for.

In this professional message board one can also expect the official spokespersons of NNA to give accurate, truthful and honest replies, which may include somethng like "unfortunately, our software is not designed to handle large data sets", instead of accusing the users and/or belittling them.

I have plenty of experience with VW's DTM not being able to model terrain data that are a breeze for competing programs (like $100 add-ons for AutoCAD), so there must be something fundamentally wrong in NNA's program.

[islandmon]

Basically, there's nothing wrong with the DTM Procedures a little patience can't fix; but they are sensitive to initial conditions and repeated re-calculations. Senor Cerveza managed to resolve his issue by starting over in a new file. This works because it eliminates the original 'temporary file' which was causing the error message.

The issue of large datasets is a non-issue , DTM procedures are universally based on TIN and therefore are sensitive to coordinate displacements not necessarily a finite number of data points. A well balanced evenly spaced dataset will produce a reliable TIN ... discontinuities in the dataset will not.

In general the 'Finland' contour problem is a fractal problem based on Log4/Log3; this limits the coherent resolution provided by the dataset before the set becomes redundant and de-coherent ( both Katie & Petri are correct ).

Over all, the frequency = number of edge divisions of the TIN triangle determines the contour 'accuracy'. Normally, this frequency should be limited to Log3/Log2 =1.6x the grid spacing. Therefore, using a fractal cardioid normal distribution ... if a DTM contour interval of 10 meters is required , then the data points should be spaced at 6 meters in order to achieve max accuracy with min data points.

[haga]

I have another dtm problem.

I use architect 12.5

after I create and update a site model with a nurbs roadways the model updates somewhat ok. But when I add a pad and update, it wacks out the roadway Sending points strait up or down thousands of feet. ? as I add more info to the site model through the use of modifiers why do previously modified objects get wacked out even though there is no fence or modifier overlaping?

Also, I wonder if I am running out of memory or computing power. VW just freezes on some calcs and site modifications.the project area is 124,000 sq M and 500 ft elevation shift. I have 1 gig ram pent 4, and nvidea ti4600 128mb

should I think of upgrading my system? - mac pro with 3 gig ram 512card, bootcamp windows xp?

[Guest]

I'm working on this problem with another customers' file. If you don't mind, can you please send the file to me?

[Guest]

Cerveza,

It's a good rule of thumb to import information into a blank document. If you didn't do that, copying and pasting would have eliminated any of the erroneous data that sometimes comes in with dxf files.

[haga]

site modifiers?

dirty poly's?

I rebuilt the site model in a blank document.

road nurbs and pad modifiers work now together again

Why are files getting corrupted?

[CS1]

I am using version 11.5.0, when creating a site model (even from as little as 10 3D locis" I recieve the error "a miscellaneous error has occured. (20, 1)"

[Guest]

Please see duplicate posting in the Architect forum.