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How can custom keypoints / descriptors be created?

asked 2015-05-28 09:54:05 -0500

Potato gravatar image

I am aware of the DescriptorExtractor class, but I wanted to know if there is a way to create my own key-points and my own descriptors. Say for example, I detect the co-ordinates of corners in an image, and I want to convert them to key-points and descriptors, How can this be done?

While researching, I have seen that descriptors, are calculated based on a 16x16 neighbourhood and using histograms. Can someone please explain how this can be achieved?

Thank you.

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answered 2015-05-28 10:41:01 -0500

thdrksdfthmn gravatar image

updated 2015-05-28 10:43:14 -0500

KeyPoint has more parameters, like point (the center), angle (where is the corner pointing to), etc, see the docs; while the descriptors may be computed via HOG (here is a nice example), on the keypoint size for example...

If you are very interested, you can get inside the code for certain implementation on git

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Thank you for the concise answer. The SO link was quite helpful. I might just have to crack open the code and take a look inside.

Potato gravatar imagePotato ( 2015-05-28 11:19:21 -0500 )edit

On the same lines, Is there a way to reverse the computation? For example, take a set of descriptors and convert it into say a floating point value?

Potato gravatar imagePotato ( 2015-05-28 13:39:25 -0500 )edit

I suppose not, because the descriptors of a keypoint is containing 32, 64, 128 or 256 values, so converting those values into one, I would not do it. Or you wanted to ask something else?

thdrksdfthmn gravatar imagethdrksdfthmn ( 2015-05-29 02:25:59 -0500 )edit
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That is what I wanted to know. What I am trying to achieve is, being able to represent the features in an image in a way that can be fed as inputs into a neural network. Do you have any ideas or suggestions for this?

Potato gravatar imagePotato ( 2015-05-29 11:07:19 -0500 )edit
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I think you shall create a new question with more explanation about your data, maybe "how to use ANN_MPL for/with my data?" ... What do you think?

thdrksdfthmn gravatar imagethdrksdfthmn ( 2015-06-01 06:48:09 -0500 )edit
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Asked: 2015-05-28 09:54:05 -0500

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Last updated: May 28 '15