Export Model

[gEEvEE]

Hi PS users,

I have a 3D model of a Roman gate that I would like to export. The camera positions are known to 2 cm accurate by using D-GPS. The idea is that I have all the vertices of the model in the WGS84 or UTM-ETRS89 coordinate reference system. However, I am unable to do so. I tried almost all possible options (binary coding on and off, different formats, different coordinate reference systems) but the export creates:
* just lines, or
* very blocky models. Even stetting the precision to 20 does not seem to help.

Does anyone have a solution for this? Cheers,

Geert

[Kjellis85]

I am not sure if this is a fix for that problem, but I have experienced something similar. If I have georeferenced a model in WGS 1984 33N, then I must choose only WGS 1984 when export the model. As I sai, not sure it is the same problem, but you could try this.

[Alexey Pasumansky]

Hello Geert,

Could you please provide the project file to us?

Also there could be a problem with non-projected geographic coordinate systems when x and y are in degrees. Due to the different scaling of the coordinates you can get highly deformed faces of the model. Please check that you are exporting model in projected coordinate system.

[gEEvEE]

Hi Alexey,

indeed, geographical coordinates just export a line. However, when I use projected coordinates (UTM 33N, ETRS89 or UTM33N WGS84), the appearance is extremely blocky. (see attachment)

I will put a similar (smaller) project file online, which has exactly the same error.

Regards, Geert

[Kjellis85]

Are you opening the exported file in meshlab? I have heard from the guys behind meshlab that they have a real big problem with viewing models that have coordinatesystems bigger than three digits before comma. There are no real work-arounds, or so I have been told. The only thing you can do is to go into the file and move the decimal separator a few steps to the left.

You could also try the meshlab forum http://sourceforge.net/projects/meshlab/forums/forum/499532

[gEEvEE]

OK, I will try but I do not really have any expectations, as I opened up the file in both Geomagic and Rapidform and these $$$$$ programs showed the same blocky appearance.

[Wishgranter]

Can upload on dropbox the scene file ? *.psz romat ? PM me with link.....

i have here Geomagic but the Polyworks suite too. Can test few things.....

[gEEvEE]

Well, not really. Images are for publication and we do not like to share them at this stage. As said, I have Geomagic, Rapidform, RiScan Pro, Meshlab, VRMesh, Cinema 4D. I tried all possible things but nothing really worked (in none of these packages).

[Wishgranter]

hmm. OK understand.....

But is here a option that you export just unreferenced model and then in other app add the coordinates ?
And can set the comma to 3decimal numbers ? make it difference ?

Can send just a 25k mesh eventuely ? just for tests

[Alexey Pasumansky]

Hello,

Seem like most of the 3D editors store coordinates in float type (and not in double) and the although the "Precision" parameter value is set to a dozen of digits they are not used when imported in the external editor.

So maybe exporting the model in local coordinates with KML file (WGS84 coordinate system) could be an alternative.
Or it is also possible to use "Shift" parameters in export model dialog.

[sflo]

Hello,

this problem has never been solved, not even in the actual version (2.4) ? I experienced the same issue with meshlab, 3D studio max, maya, etc... every single software I tried gives blocky models totally ugly.
Problem is that for some operations the projected model is absolutely needed and the local coordinates model is totally useless. So how is it possible to proceed 4 years after this issue was firstly discussed ?

Cordially,

[Alexey Pasumansky]

Hello sflo,

I'm not sure it is PhotoScan problem actually, when the external applications store the coordinate information in float format, thus limiting the number of significant digits to eight.
If you open the mesh models exported in geographic coordinates in any text editor you'll see that PhotoScan saves the coordinate information correctly.

However, if you have the experience with properly working models in UTM coordinates with the mentioned packages (like MeshLab) maybe you can share the working example of such model and the required workflow steps on the model import to those application?

[sflo]

Hello Allexey,

thank you for this fast answer.
I usually  work on 3gb models and 10 gb psz files, so it is difficult to share one of them.
I use Lambert93 2154 coordinates system but also notes same issues with WGS and all others.
Of course, I have no doubt that Photoscan stores the coordinates information properly and I am aware that the problem is the importation in other software. But why don't you simply propose an option to export for "meshlab and co" reducing the number of significant digits ?

Nevertheless, do you have any procedure to reduce manually the accuracy to 8 significant digits when exporting a model? Besides it is very bad for me to proceed working from 1 cm models accuracy to 10 cm model accuracy, I don't see any other solution.

Thank you again.

[Alexey Pasumansky]

Hello sflo,

You can use Offset fields in the Export Model dialog to subtract high numbers from the coordinates, like millions and thousands of meters. Would it work as a workaround for you?

[sflo]

Well, I can't see any "Offset fields" option in the Export Model dialog