Adding GCP after mosaic is created

[aggieair]

Hello all,

I'm running PhotoScan 1.0.4.1847.

I successfully created an RGB mosaic of a stretch of river.  I did this without ground control at first.  It went smoothly and the end mosaic looks good.  400m AGL, pixel resolution should be 13 cm.  Canon S95.

If ground crew does not lay out air targets for the flight, we use features from a basemap that we can get online.  However, I need a mosaic first to see what features I can see in the mosaic and in the basemap.  Now I have a list of GCP and their coordinates ready to import.

Up to this point, I've been opening the existing project, placing my markers in images, importing the GCP file, turning off all the image cameras, changing the projection, running optimization - then going to Build Dense Cloud again to redo the points.

I usually get the error "Can't Build Dense Cloud."  Most of the time, after messing around with it a bit (closing reopening, etc), it suddenly works and I don't know why.  If I can redo the dense point clouse, I continue with my operations (Mesh, Texture) to make a new mosaic.

However, on this particular project I cannot get past the "Can't Build Dense Cloud" error.

I tried to realign photos (this is after I put in all the GCP) and that only procued half of a project.

What is the right way to add GCP in?  Start over with a new project, align photos, then add GCP markers?

[aggieair]

OK, it seems I do not have to redo the dense point cloud after I add GCP.

I started right up with Build Mesh and it included all my GCP in the new mosaic.

I still would like to know if I'm going about it correctly!

[aggieair]

Anyone?  So far when i add any additional GCP, I go through all these steps again to create my Mosaic_version2: Optimization / Point Cloud / Mesh / Texture .

If that does not work out, then I start all the way from Align Photos on occasion.

Normally should I go through all the steps again minus the Align Photos part?  What is the best order when you already have a mosaic, but you just add one more GCP, etc?

Any advice would be appreciated. 

If I do not need to do all those steps above, this would save me time in the long run.

[gatsri]

Best way to add GCP is after the Align-Step. becose when you have the dense point cloud, and you optimise camera parameters, you will lose it.

So i think there is no other way than rerun the whole project, beginn at pointcloud - step.

Hope this helps.

[aggieair]

Thank you for the reply!  So start right after the Align photos (only do once) and also do not do the Optimize option after adding new points.

[Johnny1607]

aggieair,

I get the same 'can't build dense cloud' after optimizing alignment with GCPs (with photos unchecked) and could only build a mesh with the sparse point cloud.

Have you found a solution for this?

I'm going to try aligning the photos again, optimize and see if that helps.

Johnny

[Alexey Pasumansky]

Hello Johnny,

Maybe you can provide a couple of screenshots of the model view, including the camera positions, sparse point cloud and bounding box?

[Johnny1607]

Hi Alexey,

Here is the camera positions...

[Johnny1607]

Actually the screenshots can be accessed from here...

http://dropbox.aber.ac.uk/?lmRrdGDT

Many thanks,

Johnny

[Alexey Pasumansky]

Hello Johnny,

Everything looks good. And what is the message in the Console pane related to the dense cloud generation? And is this problem reproducible on any dataset on on this particular one?

[Johnny1607]

Message says 'Can't build dense cloud' and I can't seem to reproduce the error with other datasets...

[Alexey Pasumansky]

Hello Johnny,

Could you please open Console pane (via View menu) and copy the output related to the dense cloud generation.

[Johnny1607]

Alexey,

I've attached the console output when the dense cloud fails to build.

Thanks for your help,

Johnny

[Alexey Pasumansky]

Hello Johnny,

According to the log information there's some missing image and also some of the image were resized or rotated.