How to select / change the Image Scale at which Keypoints are computed

The Keypoints Image Scale defines the image size at which the keypoints are extracted in comparison to the initial size of the images. The image scale can be chosen among the following values:

  • 1 (Original image size) (default): This is usually the recommended image scale value.
  • 2 (Double image size): This scale is recommended for images with a low resolution, e.g. 640x320 pixels. Thereby, more keypoints can be extracted and this will have a positive influence on the accuracy of the results.
  • 1/2 (Half image size): This scale can be used to speed up processing for large projects with high overlap. However, this will usually result in a slightly reduced accuracy as less keypoints will be extracted. This scale is also recommended for blurry or low textured images, which usually results in better outputs than the default scale.
  • 1/4 (Quarter image size): This scale can be used to speed up processing for large projects with high overlap. However, this will usually result in a slightly reduced accuracy as less keypoints will be extracted. This scale is also recommended for blurry or low textured images, which usually results in better outputs than the default scale.
  • 1/8 (Eighth image size): This scale can be used to speed up processing for large projects with high overlap. However, this will usually result in a slightly reduced accuracy as less keypoints will be extracted. 

 Changing the image scale at which keypoints are computed

1. On the Menu bar, click Process > Processing Options...

2. On the Processing Options pop-up, click 1. Initial Processing.
3. Under the tab General, on the section Keypoints Image Scale, select Custom.
4. Click on the Image Scale drop-down menu and select the desired image scale.
5. Click OK.

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