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Author Topic: UTM Model Export Failing  (Read 3260 times)

ecfisher

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UTM Model Export Failing
« on: February 27, 2017, 06:51:06 PM »
Hi all,

I've seen similar posts about this issue in the past, but no resolution so I am posing the question again, please excuse me if there is a solution and I just haven't encountered it on the forums yet.

I have a model of a cave, which I have georectified to UTM Zone 35 South within AgiSoft Pro version 1.3.  I am trying to export the model as a DAE or 3DS file so that I can integrate it into my 3D GIS databases within ESRI ArcScene and ArcGIS Pro.  The Agisoft Project settings are set to UTM Zone 35 South, but when I export my model and set the output coordinate system to either Zone 35 South or to generic WGS84 then the model renders in ArcGIS as a block mess.  The position if fine, but the model itself is corrupted.  If I export the model in local coordinates then the model looks perfectly fine in ArcGIS, but the geographic position is completely off.  I've tried shifting the exported UTM model with no luck and I have, at this point, probably exported about 5 dozen different models, testing various parameters, again with no luck.  Does anyone have a workaround?

Best,

Erich

Alexey Pasumansky

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Re: UTM Model Export Failing
« Reply #1 on: February 27, 2017, 07:10:14 PM »
Hello Erich,

If you are exporting in WGS84, the units along X and Y are different (degrees), so if ArcGIS doesn't understand mesh model in such coordinate systems, then it will be trying to display the model, like the units are the same for X and Y.

The problem with UTM export may be related to the rounding issue, if ArcGIS stores the coordinates of the mesh vertices in float format.
The recommendation for the latter case is to use Offset fields in the Export Model dialog to subtract large values from the X and Y coordinates.
Best regards,
Alexey Pasumansky,
Agisoft LLC

ecfisher

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Re: UTM Model Export Failing
« Reply #2 on: February 27, 2017, 07:19:11 PM »
Hi Alexey,

Thanks for responding so quickly.  I'm not sure I follow.  UTM units are in meters on the Northing (Y), Easting (X), and Elevation (Z) axes, not degrees?  Do you mean the different coordinate value sizes due to the systems of false northings and false eastings? 

I will try to export the model using offsets.  Are the offset boxes in the order FOR "X", "Y", and "Z" offsets? Should I also use negative values?

Thanks for you help, I really appreciate it!

Erich

Alexey Pasumansky

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Re: UTM Model Export Failing
« Reply #3 on: February 27, 2017, 09:45:01 PM »
Thanks for responding so quickly.  I'm not sure I follow.  UTM units are in meters on the Northing (Y), Easting (X), and Elevation (Z) axes, not degrees?  Do you mean the different coordinate value sizes due to the systems of false northings and false eastings? 

I will try to export the model using offsets.  Are the offset boxes in the order FOR "X", "Y", and "Z" offsets? Should I also use negative values?
Hello Erich,

You've mentioned that you have problems both in UTM zone 35 and WGS84, or I understood it incorrectly? So the reason of issues for those cases are different.

For more information about offsets, please check the second page of the following thread:
http://www.agisoft.com/forum/index.php?topic=452.msg26554#msg26554
The values should be positive.
Best regards,
Alexey Pasumansky,
Agisoft LLC

AFB

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Re: UTM Model Export Failing
« Reply #4 on: April 13, 2018, 11:10:41 AM »
Hi All,

I thought that I would revive this post, as I am having the same issue as Erich with the export model function of Agisoft. There doesn't appear to be a satisfactory work around for this as of April 2018. I am exporting 3D models (both .dae and .wrl, same problem with both) into an ArcScene (10.5) environment, using the same coordinate system - WGS 84 UTM zone 35S.

This issue has been around for some time, and a few years ago a team from the DARK lab at LUND university posted a work around for the model geometry issue in ArcScene - export a WGS model from PS, as well as a model in LOCAL coordinates - import first the WGS model into ArcScene (to a file geodatabase), edit the model and select it using the edit placement tool, then replace the model with the LOCAL version. This fixes the geometry problem most of the time, however all the models that I have used this on are now out by a few cms. One could 'move' the model using the edit - move function, however this is a clunky process, crashes often and is not really satisfactory when we're dealing with many models.

Now as I understand it (from reading many posts on these forums that deal with similar problems), the issue isnt so much with PS as with other software storing the coordinates in a different format (float vs double?).  A work around for this problem has been to use the SHIFT functionality in PS when exporting the model. I have had success with removing the first three digits from the GCPs (eg from X: 363999.999 to 999.999). However, this is not exactly satisfactory when we our aim is to integrate the models with a large volume of data collected in UTM, say for artefacts that have been piece provenanced using a total station (as is the case for both Erich and I). Unless all the spatial data is appended in this way, the shift function doesnt appear to help with this issue. From what I can see, PS adds 6 decimal places to the UTM coordinates (eg. X: 363999.999000), and I am wondering if this might be where the problem lies? Is it possible to use the shift function to remove the last three decimals and would this work?

One aspect of this problem that I am finding hard to understand is the export of LAS files (dense clouds). I routinely export a LAS and a 3D model for all models - the LAS files import into ArcScene in the correct position, without any issues. It doesnt appear to me that anything has changed in the coordinate system or the way that PS exports the coordinates, and it doesnt seem to have any issues with ArcScene. This is also the case for orthomosaics and DEMs (they work fine in my experience. So it appears the problem is isolated to 3D models.

Is there any way that the PS team could create a function for exporting to other software to change the format that the coordinate system is stored in and hopefully solve this issue?

If anyone knows of any workarounds that avoid appending the coordinate system please post them! I cannot presently see a useful solution, unless we are happy to tolerate inaccurate models in the correct coordinate system. Perhaps a transformation from a projected to a geographic coordinate system would do the trick? This would, however, be a time costly solution if we are dealing with many models..

Regards,
Alex