Answer Day - Civil 3D Surfaces

[fcernst]

How old is the programming code for Civil 3D surface creation and analysis? Is it still the same code from back in the Softdesk/LDD era?

Reason I ask is that it is not performing well (or at all) on new computers with data such as that derived from the USGS or LIDAR for hydrologic and other studies. It is also not using the available processor and memory resources on the new computers.

Please see this thread:

https://forums.autodesk.com/t5/autocad-civil-3d-forum/answer-day-civil-3d-performance-vs-games/td-p/...

[Matt.Anderson]

Try the smallest GRID size together with the SMALLEST stream accumulation value. (Both sliders to the left)

Number of points and who collects them as no bearing on the analysis.  Despite the identical nature of the tiny surfaces - these calculations operate on different assumptions and different calculations to arrive at a watershed.

[Matt.Anderson]

Read this: http://hydrology.usu.edu/taudem/taudem5/CSDMS_tauDEM_workshop.pptx

[fcernst]

Yes, I have set both to the smallest and it still fails..

Did you ever have luck with Infraworks identifying small basins, say 1 acre or less?

[Matt.Anderson]

Yes, we did.  I don't recall the smallest area - but we put that in the slider image for the smallest accumulation that would be expected.  

Review the PPT to understand how those two values play together.  

The only item I can see that might hinder the analysis of your model is the "filling" of the terrain prior to the accumulation.  The depression filling is likely altering the stream accumulation path.  We never really took the next step with hydrocorrecting with a culvert, but that is how they do it with TauDEM on GIS today where you burn in your culvert crossings so as to maintain a continuous flow path across the terrain.