WHEN IN THE PROGRAM IS OK, BUT WHEN EXPORT ORTHOMOSAIC :(

[cabecinhas]

Hi. I don't know what am I doing wrong.

When creating a orthomosaic in AgisoftPhotoScan, after build geometry the result (before export) seems to me ok, but after exporting the orthomosaic the result gets really bad.

could anyone help me on that?

Thank you very much

[Alexey Pasumansky]

Hello cabecinhas,

Looks like you are exporting the orthophoto in the planar projection, or the model is not referenced correctly.


Please note that for correct georeferencing you need to use at least three points (camera positions and/or GCPs) that do not lay on the same line.

[cabecinhas]

Hi, Alexey.

I did export in Geographic mode

All my photos are referenced. As you could see in the model panel they look good(the probme is when exporting).

Actually I don't have any GCPs since I'm using only 3 photos on this project.

Could you give me any idea?

Tks

[Alexey Pasumansky]

Hello cabecinhas,

If all three photos are from the same flight line then there is a rotational degree of freedom around this line. If you have overlapping images from another flight line I recommend to add them into your test project and process them together with the current images.

Alternative way (for testing purposes only, since it is very inaccurate) is to place GCP in the center of the middle image and assign the same X, Y coordinates that were used for corresponding camera center, and Z as (camera Z - flying altitude), then press Update button. In this case Z-axis should be looking upward relatively to the model in the Model view.

[cabecinhas]

Yes.. the photos were taken in the same flight. What do  you mean by rotational degre?

[Alexey Pasumansky]

I meant that you can not reference the model correctly using only three points laying on the same line.

[cabecinhas]

So It is mandatory to creage GCPs?

[Alexey Pasumansky]

No, if you have at least two line flight or non-linear single flight line.

[cabecinhas]

ok..

Well I have 3 geotagged line pictures with about 70% of overlapping

I'm sorry to be here and ask this much things..

[pvandyke]

cabecinhas,

The GCP will help tell PhotoScan which direction is horizontal in your model.  It may not be the most accurate, but you could try using Google Earth to get X,Y,Z values for the ground control.

Once the horizontal (X,Y) is figured out, exporting your orthomosaic should give you the results that you desire.

I've been using this method (along with current imagery from our GIS system) to orthomosaic old B&W air photography from the early 50's.