contour detail

[gov_colin]

i have been extremely disapointed with the dtm processer so far, in that it tends to round off corners of contours to the point where important detail is lost. i have experimented (to no avail) with different ways of increasing the detail of the triangulation process.

has anybody mastered the site model generator tool within the boundaries of the tool itself? (in other words, i don't want to have to convert to mesh or any junk like that).

gov

[Robert Anderson]

gov_colin, can you send me your file? I'd like to see the effect you are referring to. Generally, the TIN (triangulated irregular network) used by the DTM uses all the actual data that you provide as "source data", no more, no less. Send the file to: randerson@nemetschek.net

[gov_colin]

rob

i would, but the original 3d polys (which i traced from a bitmap) are long gone, so it's impossible to compare source data with 3d data at this point. all I'm trying to describe is a lack of sensitivity within the procesor.

in other words:

i understand that the site model tool can build an existing and proposed dtm. however since i'm working with an existing house and i already have the existing contours, i draw in the contours as having a flat pad for the footprint of the house (in an attempt to get around the site modifier tool which i have never gotten to work).

another question:

i accidently created my source data on a layer with diefferent scale of that of the building model that it would be paired up with. instead of fixing the source data, i just wen into the symbol and scaled eveything appropriately. however now, i can't use the site modifier tool because every time i process the beds/pads, the site model reverts back to the original scale, making it impossible to edit. any suggestions?

sorry for typing so much.

[Robert Anderson]

Colin, the scale of the layer does not matter. You should never have to be concerned with scale, just draw everything in real world dimensions always. Scale is just display.

[gov_colin]

sorry, i didn't explain. i linked the dtm layer with the building model layer.

[gov_colin]

hey last question and then I'l stop...

would loading up the 3d polys with vertices make for a more detailed model?

[islandmon]

gov- its really all about the contour intervals and the grid placement of your 3D loci to set-up the Existing DTM . Any changes you make to the EXST 3D Loci require re-doing the Existing and rebuilding the symbol. Proposed works from the Existing data-set and rebuilds the TIN based on your declared Site Modifiers regardless of the layers ( chosen from the PIO ).

Smoothing of contours is nice but often complicates the final editing.

By Final Editing , I mean that once the DTMs are completed to your satisfaction you may need to go into the Proposed Symbol and edit it to 'simplify' the 3D presentation and normalize the 3D Mesh ( eliminating bands of high contour areas between Site Modifiers)... both science & art ... to get what you are seeking in terms of information displayed by the end-product.

DTM is NEVER perfect because the TIN is a compromise and Site Modifiers require polygonal fences to help define the boundaries of the calculations. If you desire a higher frequency TIN then just declare a closer spacing of the contours. Just for fun take an existing DTM and change the contour spacing from 1m to 1cm or 1ft >1in. ; )