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Bug in utils.compute_angle_weights_1d
#7
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utils.compute_angle_weights_1d
I will try to explain what is happening:
For your -60°/+60° case, you should probably disable weighting the angles (if they are evenly distributed). Otherwise, I would be open to introducing another keyword argument that defines the desired spread of the angles... Cheers! |
@paulmueller thank you for looking into this. Yes, I disabled weighting. I just wanted to report the behavior I found odd when I was testing this function out. In the point 1., I understand that 180° must be covered for a proper reconstruction, unfortunately, this is not what you can measure in a real microscope. Case 2. makes sense, OK. Case 3. looks like a bug indeed. Might be just solved by raising an error, because I also can not imagine a case where somebody would actually have coverage >180°. Cheers |
Maybe the docs could also be clearer about point 1. |
I believe this function should return a flat line in case all the angles in theta are equidistant.
This is true in this example:
But there seems to be a problem in the following cases:
1) Not a full circle
But it is not the case on the edge angles (first and last in the vector) if we do not do a full circle:
2) Edges lying on the same line
And then there is another problem, if the edge angles lie on the same line through the origin of the unit circle:
3) Edges are the same angle
Also, when the edge angles are the same, we get a 0 weight on the 90°, which does not make sense IMO:
Summary
Either this is not a correct implementation, or I do not understand the intentions with this function.
When I try to reconstruct a tomogram from the projections recorded at the usual tilt angles (-60°, 60°), the two edge tilts get extremely big weights and the reconstruction looks terrible. Thanks for looking at this.
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