Author Topic: Wrong number of Key Points when using Batch process  (Read 2030 times)


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Wrong number of Key Points when using Batch process
« on: February 07, 2017, 03:49:57 PM »
I use Photoscan (v1.2.6)  to reconstruct a memorial.
For this, I first aligned the images using "Workflow > Align Photos..." from the menu. I entered the amount of Key points (40,000) and Tie points (4,000) to be found by the process.
The result was the number of 42,859 Key points that were found, which is ok in my opinion.

I then experimented with the number of Key points, so I created several chunks with the same photos and sterted the Batch progress while typing in the different amounts for every chunk (10,000, 20,000, 40,000, 50,000, 70,000, 100,000, 200,000) and the respectively same amount of Tie points.

After the process I was wondering about the results.
Every Chunk had about ten times the amount of Points in the Point cloud compared to the values I entered (see images)

So is this a kind of bug? Or do I do something wrong?

Thank you in advance

Alexey Pasumansky

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Re: Wrong number of Key Points when using Batch process
« Reply #1 on: February 07, 2017, 07:03:03 PM »
Hello Manuel,

Tie point limit actually defines the threshold for the number of projections of tie points to be present on each photo, whereas the key point limit defines the upper threshold of the features that are detected on each photo on the very first step of camera alignment procedure.

So it is not the number of tie points in the cloud that you are defining, but the number of projections of the tie points that can be present on every photo.
Best regards,
Alexey Pasumansky,
Agisoft LLC