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Ashwinning / libmv

Automatically exported from code.google.com/p/libmv
MIT License
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BoxIntegral gives negative values #1

Closed GoogleCodeExporter closed 9 years ago

GoogleCodeExporter commented 9 years ago 
What steps will reproduce the problem?
1. Launch tvr in debug mode.
2. Load the two attached images.
3. Click the Compute features option in the menu.

The program stops because of an assert in UnsafeBoxFilter. The assert
checks that the box integral of a positive image is positive, which is not
the case.

Original issue reported on code.google.com by pau.garg...@gmail.com on 26 Apr 2009 at 6:15

Attachments:

GoogleCodeExporter commented 9 years ago 
After some investigation, I see that the problem is floating point precision. 
The box
integral code triggers catastrophic cancellation. The proper solution is to 
switch to
using either int32's (max image size would be ~4k x 4k) or int64's for the 
integral
image.

I'm working on a fix.

Original comment by mie...@gmail.com on 1 Jul 2009 at 7:04

GoogleCodeExporter commented 9 years ago 
I switched to use an integer matrix for the integral image. Unfortunately SURF
doesn't seem to work reliably.

Original comment by mie...@gmail.com on 1 Jul 2009 at 10:14