DTM - Bug in calculating cut / fill information ?

[Frank Vermeersch]

When you draw a pad with a fence around it in the DTM, the cut and fill information seems to be correct.

When you try to use several pads with a different slope in %, where the pads getting used each other (endpoint of the 1e slope = beginpoint of the 2e slope), the cut and fill information is more than double instead of calculating each pad seperate and take the sum of them.

Has anyone an explanation of it?

thx Frank

[Frank Vermeersch]

Hi

Here is my file. Try this: cut information when calculating DTM = 763 m?

Try to calculate each DTM-object seperate. Than the sum = about 300 m?

regards Frank

[orangeman]

Frank,

you're right. There is a bug in the calculation of cut and fill. We had the problem a couple of month ago over here in Germany. We disussed it on the german support board. One user had already talked to Nemetschek about it and found out that they knew about the bug. Hopefully they fix it soon!

When you keep the DTM very plain and simple it gives you the right numbers. Good enough for a rough estimate. But I wouldn't trust it if its getting more complex even if it seems to be correct.

:-(

[Art V]

Frank,

The user manual or the quickstart guide mentions that pad should not intersect another pad or a fence (talud) or you will get inaccurate results for the cut and fill. Fences can intersect each other without problems. (At least that is what the documentation says)

Unfortunately I don't know if touching pads do count as intersecting pads or not.

In your file, the pads are intersecting with fences, so that might explain the results. Maybe you could try creating a single fence for all pads together and see if that solves the problem.

(Select all pads and then create the fence)

I also noticed that your fences/taluds have a height.

When I used the cut and fill the first time, I gave the talud the same Z value as the DTM modifier and the cut&fill values were approximately twice of what it should have been. One I recreated them and left the Z value of the taluds at zero, the results were much closer to the rough estimates.

This could be another possible explanation for the doubling you got.