Solaris Tut 5 - Sean Lewkiw: Pruning for Sop Jitter

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In Tut 5 at one stage Sean is saying to prune the jars from the scene(Lops) so that the next operations(Sop Jitter) will go faster.

Well, so far my understanding of USD is that when you doing something like using the Prune Lop, your not really removing it - Just removing it from the current ‘view’.(underneath it's still there)

After pruning and applying an Extract Instances Lop then a Sop Modify Lop - Then going inside the Sop Modify Lop and using a Point Jitter Sop - One Can see not only the intended Jars being moved but also the ones intended to be ‘pruned’(the leafy type geo seen in the pics).

So unless there is a bug with the viewport(I created new scene windows to be sure), it doesn't appear that pruning really helps at all for applying the point jitter.

I put in a switch node in the Sop Modify Lop and with unpack USD, Partition and delete nodes separated the intended ‘prims’ to have only Jitter applied too.

From the screen shots you can see it seems to have ‘worked’. But again, I really don't know if this is just a viewport ‘issue’.

I'm not able to test the two different approaches as my system is already at max for resources on this tut and crashes easily.

Just wondering if anyone has an opinion as to what really might be going on.( would pruning ‘prims’ really help in subsequent operations like point jitter)

************

As an addendum for completeness although not affecting the above ‘issue’. In the first two screen shoots I provide I use a pack node which has the effect of creating two new layers when brought back into the Lop context.

By adding the path attribute in the pack node and in a prim wrangle add the same string name attribute of ‘RBD’, the merged sop geometry is seen as one like in the original lop scene.
Edited by BabaJ - Dec. 22, 2019 13:40:23

Attachments:
LOP Sop Jitter Include Prune.jpg (221.0 KB)
LOP Sop Jitter Exclude Prune.jpg (247.4 KB)
LOP Sop Jitter Addendum.jpg (199.4 KB)

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I think I found the issue.


The node sequence after the switch and up to the sopmodify(that has jitter node inside) is:

Prune > Layerbreak > Prune > ExtractInstances

For the first prune he specifically says to the method to Deactivate(the defualt is Make Invisible).

The second prune he does not say set to Deactivate so it remains as Make Invisible.

With the second set as Deactivate the jitter performs much more quickly and I don't see the foliage in the viewport. So this must be the answer.

Might be a good idea to adjust the tutorial to specifically have the prune set to Deactivate(at least for beginners this might be useful is saving confusion).
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Thanks for sharing your fix! I'd be interested in looking at this tutorial series, does it still exist on the internet?
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