Flag Keypoints with lasthin

[Itzstein, Gregory]

Hi,

 

Can lasthin utilise a –flag_as_keypoint option to keep the thinned points in the ground class and assign the keypoint flag?

 

Regards,

Greg.

 

 

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[Martin Isenburg]

Hello Greg,

this is already possibly as shown below. Note however that these are not "true" keypoints as there are no error guarantees in terms of how far the surface defined from the subset of ground points maked as keypoints will deviate from the surface of all ground points.

lasthin -i ..\data\fusa.laz ^

           -ignore_class 1 3 4 5 6 7 ^

           -step 4 -classify_as 8 ^

           -odix _fake_kp -olaz

lasview -i ..\data\fusa_fake_kp.laz 

Press the <m>-key (like <m>asspoints) to visualize the (red) keypoints only and the <=>-key a few times to increase the point size. There is one new option in lasthin (as of the latest release 150828) so that instead of the default '-lowest', the most '-central' of all points falling into each grid cell is kept. The difference in the result is visually quite striking as you can see in the attached screen shots: it leads to an as regular as possible spacing of the points reclassified as 'keypoints' ...

lasthin -i ..\data\fusa.laz ^

           -ignore_class 1 3 4 5 6 7 ^

           -step 4 -central -classify_as 8 ^

           -odix _fake_kp -olaz

lasview -i ..\data\fusa_fake_kp.laz

Press <m> again followed by the <=>-key a few times. Or were you asking about using the keypoint flag instead of the keypoint classification?

Martin @rapidlasso

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[Itzstein, Gregory]

Hi Martin,

 

Yes I am required to use the keypoint flag and keep the thinned points in class 2.

 

I am attempting to demonstrate that the keypoint flag can be used for an example dataset and acknowledge that these won’t be true keypoints.

 

Regards,

Greg.

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[Itzstein, Gregory]

Hi Martin,

Is there any update available on the -keypoint flag option?

Regards,

Greg.

Greg Itzstein

AAM Pty Ltd

M: +61 (0)408 416 908

Skype Name: gregitzstein