Sorting points by ID expression

[cgcris]

Hi guys,

 

The old chesnut of sorting by point ID after deleting a bunch of them. 

 

I am attaching a file, I am using a sort sop and setting the expression to ID.

 

I am expecting the points to revert to their initial point number after the sort.

 

Why is this not working?

 

Any help would be appreciated.

 

thanks in advance,

Cris

point_sort_by_id.hip

[Skybar]

Well you are deleting points, so to get the same point number after the delete is impossible. That's why creating an ID is good, because you have their initial point number in that attribute instead.

[cgcris]

I thought about that, but then I saw this example from Jeff that does just that:

 

http://www.sidefx.com/index.php?option=com_forum&Itemid=172&page=viewtopic&p=101085

 

kill_splits_with_constistent_sort.hip

 

I guess because he is using particles is different?

 

Also note that sorting by other method does work..

 

Thanks,

C

Edited February 25, 2016 by cgcris

[Skybar]

His point count is the same all the time. If you have 100 points and delete the first 50, it is impossible to then have a point with point number 100 since you only have 50 points.

[cgcris]

His point count is the same all the time. If you have 100 points and delete the first 50, it is impossible to then have a point with point number 100 since you only have 50 points.

 

 

I see your "point" now, thanks for the explanation!

 

I am culling some lidar data with the camera frustum, but it's difficult to work with is point ID is changing on everyframe.

 

Cheers

[anim]

by point ID you mean the actual ptnum?

if your lidar data is static or has consistent topology before delete, you can just create id attribute on it, which will stay the same after delete and you can use that instead of ptnum, unless I misunderstand your problem