Measurements seem to be incorrect.

[Oscar]

We are still evaluating 3DF, generally we like it but we've run into a problem that is preventing us from adopting it as our preferred product. When using the 3DF desktop product we measure a known element to confirm that we have previously measured on the ground is correct. When we export the obj file and view it through NIRA or Sketchfab the measurements are different. Have we missed a setting in the Export or is this something that the developers would like to know about? Two comparative photos are attached. The smaller image is a screen capture whilst using 3DF, the larger is from a NIRa presentation.

[cam3d]

Hi Oscar -

All 3D reconstructions made by 3DF Zephyr are subject to an arbitrary scale factor, a translation and a rotation.

OBJ files are unit-less and different programs have different default measurements/scale.

In this case, assuming the units in Zephyr are considered Meters, this correlates with Yards*2 in NIRA.

If you wish to 'set' your units to represent a certain metric (cm/inch/etc...) you need to have a known distance in the scene and use that for re-scaling. In the full version of 3DF Zephyr you can do it easily directly using control points and control distances:

https://www.3dflow.net/technology/documents/3df-zephyr-tutorials/tutorial-manage-control-points-distances-3df-zephyr

You can make measurements and scale things in 3DF Zephyr Free/Lite but it's less accurate without the use of control points:

https://support.3dflow.net/support/solutions/articles/43000052981-how-to-scale-and-make-measurements-with-zephyr-free-and-lite

[Wekedoo]

Hi Oscar -

All 3D reconstructions made by 3DF Zephyr are subject to an arbitrary scale factor, a translation and a rotation.

OBJ files are unit-less and different programs have different default measurements/scale.

In this case, assuming the units in Zephyr are considered Meters, this correlates with Yards*2 in NIRA.

If you wish to 'set' your units to represent a certain metric (cm/inch/etc...) you need to have a known distance in the scene and use that for re-scaling. In the full version of 3DF Zephyr you can do it easily directly using control points and control distances:

https://www.3dflow.net/technology/documents/3df-zephyr-tutorials/tutorial-manage-control-points-distances-3df-zephyr

You can make measurements and scale things in 3DF Zephyr Free/Lite but it's less accurate without the use of control points:

https://support.3dflow.net/support/s...-free-and-lite

Yes thats all understandable, but still inside Zephyr. I have same issue. We need to be able to export model e.g. to NIRA and have correct measurements. We have precise measurements in Zephyr but what matters more is to have them on presenting platform like NIRA for our customers.

[cam3d]

Hi Wekedoo - If the measurements are correct in Zephyr there isn't a lot we can do if the units are interpreted different in a third party program. I recommend reaching out to NIRA support to see if they have a solution for this.

[cam3d]

Re: Coordinate systems in NIRA: https://help.nira.app/hc/en-us/artic...erenced-files-

[Roberto]

Hello,

We found the issue. When exporting from Zephyr directly through Nira and Sketchfab, we always convert double-precision coordinates to single-precision as the viewers don't support double-precision data. The model is thus centered, rescaled, and rotated. Since rescaling is not always necessary (e.g., if it's already in meters, the numbers are not huge). I've added a check to rescale only if strictly necessary. The fix will be available in the next minor patch