Exporting Orthomosiac

[Origin Surveyors]

Hi

When exporting an orthomosiac from Agisoft, it is utilising the projection I have nominated, but not the corrections obtained by the markers.

That is, it is exporting MGA Z55, but not the final adjustment obtained by placing the markers.

The photo position within Metashape is fine, the spray marks on site sit directly over the marker coordinates, but for some reason this information is not carried through on export, and it is as if the position hasn't had the corrections previously calculated by the markers when I view the exported image in a CAD program.

Any help on how to get the orthomosiac to export in the final calculated position obtained by marker alignment would be appreciated.

Regards

Brett

[SAV]

Hi Brett,

There are a few things that could lead to this issue.

1) Make sure to have each GCP (accurately) linked/marked in at least 4 pictures (check PROJECTIONS column for cameras within the reference pane)
2) In the Reference pane, make sure that the markers you want to use are checked
3) Make sure that the marker coordinate reference system is set to MGA Z55 (should be EPSG::28355)
4) Before computing the dense point cloud, mesh, DEM or orthophoto make sure to run OPTIMIZE CAMERAS.
5) Make sure to choose MGA Z55 as coordinate reference system when finally exporting your orthomosaic.

All the best.

Regards,
SAV

[Origin Surveyors]

Thank you mate.

All of the above seems ok, I think maybe it has to do with the CAD package reading the TIF but not reading the associated TFW file?

I can input the TFW corrections in manually when I import them into CAD, though I'm not sure what all the parameters for each field are.

The easting and northing are obvious, though the others I don't know.

? = 0.0276442
? = 0
? = 0
? = -0.0276442
Easting = 659419.784772277
Northing = 7712026.76188448

Would you be able to help me out with what the first 4 parameters in the TFW file stand for SAV?

Thanks again for any help you can provide.

Brett

[WSurvey]

Thank you mate.

All of the above seems ok, I think maybe it has to do with the CAD package reading the TIF but not reading the associated TFW file?

I can input the TFW corrections in manually when I import them into CAD, though I'm not sure what all the parameters for each field are.

The easting and northing are obvious, though the others I don't know.

? = 0.0276442
? = 0
? = 0
? = -0.0276442
Easting = 659419.784772277
Northing = 7712026.76188448

Would you be able to help me out with what the first 4 parameters in the TFW file stand for SAV?

Thanks again for any help you can provide.

Brett

TFW parameters:

Pixel width component in E direction
Pixel width component in N direction
Pixel height component in E direction
Pixel height component in N direction
E coordinate of centre of top left pixel
N coordinate of centre of top left pixel

https://en.wikipedia.org/wiki/World_file

[Origin Surveyors]

Thanks Wsurveys, appreciate it.

Interesting they don't directly define rotation but define it by a pixel width related to a square plane. Will have to calc the rotation manually.

Cheers.

[PROBERT1968]

One thing to keep in mind, the blue flag you marked in Metashape may look like it is actually 2D but it is really a 3D. This cause the Marker to pinpoint not where you wanted

For example, when I work on old aerial photos and I use ArcGIS Pro and mark one feature there and then you input it in Metashape. When you run optimize it, and you can export shapefiles the markers from Metashape and you then import it in ArcGIS Pro . I can see that it is in 3D, so I had to change it to 2D so the markers should be exactly where you wanted the mark to be..

I hope that helps or if that makes sense to you. Let me know..

[Origin Surveyors]

Thanks PROBERT1968

I compare the marker co-ordinate to my survey control file to confirm its location. (Which should match as that is where they come from)

But I see what you're saying, you only confirm the photo location visually.

I don't think that's what the problem is here as the error within 12d is pretty well the exact errors shown for each marker adjustment residual. It's as though it's exporting only the projection without the adjustment. Which would make sense if it's not reading the TFW I think....

I'm pretty sure I optimised cameras, though I can't recall what stage in the process this was done.

Thanks for the tip with the flag colour PROBERT1968, I didn't know about that!

[SAV]

I'm pretty sure I optimised cameras, though I can't recall what stage in the process this was done.

Right click on the chunk in the Workspace pane and choose SHOW INFO. If you optimized your cameras, then it would be shown in the list.

Regards,
SAV