Amanda P
Legendary Member
- Location
- York. Well, York-ish...
I want to do some work which involves photographing things from a tower, then analysing the distances between the things. (If you've followed my postings, you won't be surprised to hear that the things are likely to be birds).
The problem is that, due to perspective, for example, a square thing won't appear square in the photo - it will appear as a foreshortened rectangle. I need to unsquadge the photo so that a square thing appears square, as it would have if it had been photographed from directly above.
This is easy to do if there is actually a square object in the photo, or at least an object whose proportions are known - I can just stretch the image in Gimp or another photo editing suite until the object appears as it should. In reality, there won't be a known object in the image, so the degree of unsquadging will have to be calculated trigonometrically from knowledge of the camera height, lens focal length and range from camera to object.
With me so far?
My question is, is there any software I could use to help me calculate the necessary unsquadging factor, and (ideally) apply it to produce orthographically corrected images?
I have done lots of homework on this, but not come up with anything very helpful yet. But you never know your luck on here, someone may be the world's expert on just this subject...
The problem is that, due to perspective, for example, a square thing won't appear square in the photo - it will appear as a foreshortened rectangle. I need to unsquadge the photo so that a square thing appears square, as it would have if it had been photographed from directly above.
This is easy to do if there is actually a square object in the photo, or at least an object whose proportions are known - I can just stretch the image in Gimp or another photo editing suite until the object appears as it should. In reality, there won't be a known object in the image, so the degree of unsquadging will have to be calculated trigonometrically from knowledge of the camera height, lens focal length and range from camera to object.
With me so far?
My question is, is there any software I could use to help me calculate the necessary unsquadging factor, and (ideally) apply it to produce orthographically corrected images?
I have done lots of homework on this, but not come up with anything very helpful yet. But you never know your luck on here, someone may be the world's expert on just this subject...
