Extract Key Points from small images

1
votes

my problem is somehow simelar to this: Extract point descriptors from small images using OpenCV

I want to extract Key Points from small images (Orb, BRISK, FAST), but if the size of the image drops below 100x160 my key point vector is empty ([]).

I cannot find a solution in the documentation.

Thank you for your help.

1
opencvfeature-detectionfeature-extraction

1 Answers

5
votes

You are trying to detect keypoints in very small images with incorrect parameters for these dimensions.

ORB, for example, filter out all points in the edge of the image taking into account an edge threshold. By decreasing the value of the edge threshold parameter you can detect keypoints in small images.

Please take a look in the documentation about the parameters of keypoint detectors and descriptors: http://docs.opencv.org/modules/features2d/doc/feature_detection_and_description.html