Bug in TIN volume surface

[DonatasAzaravicius]

Hi,

I think I found bug in TIN volume surface. I made video and attached it.

I have two TIN surfaces. One big and one smaller. I made TIN volume surface from them and got TIN volume surface only where they intersect. Made data shortcut to TIN volume surface and promoted it to other drawing. Then I added boundary to TIN surface bigger then the surface, but surface not only got cut to boundary, but got extended beyond it's possible boundary. Where here should not be any TIN surface and here it took values from bigger TIN surface it was made from.

I think TIN volume surface should not save data from it's one parent surface if here are no second parent surface because it will not be volume data. And I think TIN surface should not keep hidden data (beyond outer boundary or inside hide boundary) then doing promote, because boundaries are not promoted.

Now TIN surface keeps more data after promote then it needs and have wrong data too. TIN volume surface (thickness surface) have data about elevation.

[Wojtek_Garczewski]

Hi @DonatasAzaravicius 

Thanks for posting. 

Based on your recording and description, I understand that the issue you mentioned is present when you add a boundary to the surface from Data Shortcut, so it becomes a new boundary for the surface and overrides previously set an outer boundary. Is this correct?

You can define multiple outer boundaries, but only the last defined outer boundary is displayed. You can use the surface definition to switch between multiple outer boundaries. Please see: About Surface Boundaries

I think you need to build your boundaries differently, so only one Boundary will be applied. Although, I want to know what is your goal that you want to achieve. 

Thanks,

Wojtek
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[DonatasAzaravicius]

Hi,

boundary are not a problem. Problem are data of TIN surface. If I add boundary who are bigger than TIN surface surface becomes bigger, but how can TIN surface become bigger if here are no points to triangulate?

First of all here are no previously set an outer boundary. The boundary are maximum boundary, because here should be no points to triangulate. So if I add bigger boundary, TIN surface should not increase, because here should be no points to triangulate and increase TIN surface. So it should only became smaller, not bigger if I add outer boundary.

But for some unknown reason TIN volume surface takes not only calculated points between two TIN surfaces (volume points), but points from parent surfaces too (elevation points).

For example: I made TIN volume surface and this TIN volume surface (without any outer or other boundaries) have 100k points (here are no more points, or at last should not be any more points), I added outer boundary to it and now this TIN volume surface have 200k points. Where did additional 100k points come from? And this points are wrong, because they value (elevation) are 100, but TIN volume surface should be only max value (elevation) 4. So this TIN volume surface have wrong points.

[Joe-Bouza]

The volume surface is defined by two surfaces the base and the comparison and only "displays" the volume where there is coverage (i.e. it makes a boundary behind the scene)

when you force the boundary to be larger you are opening the window for the data from base surface to "display"

I do not see it as a bug. you are trying to use the software in a way that the developer did not intend.

Why do you feel compelled to add a larger boundary to the volume surface?

[DonatasAzaravicius]

I started using AutoCAD Civil 3D from 2010 version and I don't remember this "functionality" in older versions. Now I use 2019 version.

I need to show TIN surface only in land posses by client, but TIN surface are not as big as land. So this boundary are land boundary and I don't wan't to make smaller boundary (to save time) and it worked before.

---

@Joe-Bouza wrote:

when you force the boundary to be larger you are opening the window for the data from base surface to "display"

I do not see it as a bug. you are trying to use the software in a way that the developer did not intend.

---

And I think this is a bug. It does not make sense to add points to volume surface from base surface. Volume surface and base surface points meaning are completely different. And it don't have any relation to me using it in a way that developers did not intend.

If I promote TIN volume surface to new drawing it is not TIN volume surface any more it is only TIN surface. It don't have base or comparison surfaces. No matter the reason why developers made decision to copy all points from base and comparison surface to volume surface (may be to save time in recalculating volume surface if one of parent surfaces change), but after promoting volume surface to new drawing it is not volume surface any more and here are no reason to have hidden points in TIN surface from base or comparison surfaces. It will only make drawing bigger and confuse users if they add bigger outer boundary. It may be understandable if this points had any use to TIN surface after volume surface are promoted to new drawing, but I don't see any use for them. Is here any use for them?

P.S.

I found one more annoying "future" in TIN surface. If you pasted one TIN surface to other TIN surface, promote TIN surface to new drawing and for some reason you need to delete some points in place where was boundary of TIN surface (but now it is middle of TIN surface) and use "Simplify Surface" command, points who was boundary points will not be deleted. You will need to delete them by hand. It is annoying and I don't see any meaning in it.

[Wojtek_Garczewski]

Hi @DonatasAzaravicius 

Thank you for reporting this odd behavior.

I was trying to reproduce it on my end, but I didn't experience the issue you described. The steps were:

1. Create two surfaces (A and B) for comparison.
2. Create TIN Volume surface (C) from those.
3. Create a DataShortcut from (C) TIN Volume surface.
4. Open New Drawing, and Promote (C) surface.
5. Add a new, smaller, outer boundary to the surface (C).
6. Surface C has been limited to the smaller boundary, and no additional information has been placed. The number of points seems to be correct.

Did I miss something? 

In that case, I would like to ask you for some further information that would allow me to troubleshoot the issue further. 

• What version of Civil 3D do you use? Can you share a Screenshot of About window from Civil 3D, please? Do you have all latest updates installed?
• Can you reproduce the same issue with other surfaces, or this is present only in the mentioned surface?
• Is it possible to share the file with us, so we can take a look at this?

I look forward to hearing from you soon and helping you with this issue.

Thanks,
Wojtek

[DonatasAzaravicius]

Hi,

it is not smaler but bigger boundary.

To check with other TIN surface I made two TIN surfaces: A (115 elevation) and B (121 elevation) and created TIN volume surface from them (surface C (6 elevation value)). Created blue boundary to add as outer boundary (TIN-Volume-Surface-Bug-ABC.dwg). Promoted C TIN volume surface to new drawing (TIN-Volume-Surface-Bug-C.dwg) and copy-pasted blue boundary polyline. Added outer boundary to C TIN surface and it have same problem.

C surface got extended to east direction and now have elevation 121.

I have added both drawings to this message.

P.S. I use AutoCAD Civil 3D 2019. Had to reinstall windows so, only today I installed AutoCAD and have no updates. At company we use only 2018 or 2019 AutoCAD because it is to much work to upgrade all to latest version and upgrade may brick TIN links.

[Joe-Bouza]

Hello @Wojtek_Garczewski  and @DonatasAzaravicius 

Your screencast, VOLUME SURFACE WITH BOUNDARY, is ready for viewing.

https://autode.sk/3gPPZ4v

I get the results but  why would you add a boundary larger than the limits of the Volume surface?

I retract my statement of intended use. Yest the boundary is available to volume surfaces but I thing the intent was for bounded  volume within the limits of the volume surface

[Joe-Bouza]

Use a bounded volume. Create you volume surface then use your land boundary to create a bounded volume you will not get extra points

[Wojtek_Garczewski]

Hi @Joe-Bouza  and @DonatasAzaravicius ,

First of all, @Joe-Bouza thank you for the screencast, and I do understand your point. However, according to @DonatasAzaravicius  explanations and provided files, behavior looks a bit strange.

The surface doesn't need to be promoted, the same is present when we paste the TIN Volume surface to the empty one. Please see my findings in the screencast below:

• TIN volume surface behavior report

 @DonatasAzaravicius  can you confirm that this is the issue you are reporting about? Surface after adding boundary to it:

As a workaround, once surface is promoted, display its triangles and extract them. Then create a new surface base on extracted 3D Faces.

The surface won't have any additional points, and you will be able to add the boundary correctly. 

I find it kind of behavior that needs to be reported to our Developers for further investigation, which I will do. 

Thank you for notifying us about this behavior. If you have any additional questions, please feel free to ask.

Thanks,

Wojtek

[DonatasAzaravicius]

Yes, this is my problem.

If I add boundary to original Volume surface the same will happen, but I thought it may be intentional, but now I think it is not. Because as shown in your screencast only points from surface B will be added to volume surface and no points from surface A. Also not all points from surface B will be added.

I have swapped base surface and comparison surface and made volume surface D. Added the same boundary and got the same results, but now only A surface points are added and not all points.

So I guess only points from comparison surface are taken to volume surface.

Don't know if this is coincidence or not:

But added points to C volume surface are almost same as D volume surface (98.25 and 98.3). And numbers 106.82 and 100 show distance to the end off comparison surface.

[DonatasAzaravicius]

First time I tried screencast and made more accurate video of problem. But I could made A and B surfaces of bigger and different width it would been better.

https://autode.sk/3gCTz1y

[DonatasAzaravicius]

I have increased area of A and B TIN surfaces and made new C and D surfaces. After adding outer boundary to C and D surfaces area have increased almost the same amount as before.

only small change. It looks to me like area will increase by 96-98 meters.

[Wojtek_Garczewski · Accepted solution]

Hi @DonatasAzaravicius ,

Thank you for the detailed information. I've shared all your findings with our Development team.

I pointed out that it looks like a possible bug, and it has to be further investigated.

For now, as a workaround, please try to use the following steps:

1. Select TIN Volume Surface, display its triangles in the style.
2. Extract Triangles from the TIN Volume Surface.
3. Create a new TIN Surface and add extracted 3D Faces as Drawing Objects.
4. Once done, add polygon as an outer boundary.

Once again, thank you for reporting this behavior to us. If you have any additional questions or comments, please feel free to ask. Thank you.

Regards,
Wojtek
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