Houdini 20.5 Nodes Render nodes

USD Stitch render node

Merges USD files representing individual frames by composing them.

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Since 18.0

Overview

This node merges multiple USD files together (usually a sequence each containing a single frame of animated data) through stitching.

Stitching combines two files, a stronger and a weaker file. The prims of the weaker file are merged into the prims of the stronger file. If the stronger prim already has an opinion about a prim or attribute, the weaker data is ignored. If the weaker layer contains prims or attributes that don’t exist in the stronger layer, the data from the weaker layer is copied into the stronger layer. If the weaker layer has new time samples for an attribute that exists in the stronger layer (but for a timecode that does not exist in the stronger layer) that time sample from the weaker layer is copied into the stronger layer.

The result of stitching together two layers is a modified version of the stronger layer. Stitching a sequence of files together involves starting with the first layer as the strongest layer, then stitching in the other layers, one at a time, each time producing a new modified version of the strongest layer with (generally) some extra data or time samples copied from each weaker layer in the sequence.

Tips

  • This ROP is very similar to the usdstitch script that comes with USD, except it can stitch many sequences of layers together in a single operation.

Parameters

Render

Click to generate the output files.

Start/End/Inc

Controls the frame number values that are used to determine the sequence of USD files that should be stitched together. No data is generated from nodes in the hip file when executing this ROP, so the frame numbers are only used to generate per-frame file names that are stitched together.

Stitch Files

The number of files sequences that this node will stitch together.

Enable

Enables or disables the stitching of a single file sequence.

Input File

File path to a USD file to stitch. This file path should the frame number, for example dance_$F.usd, so that at each frame a different USD file gets stitched in with the others in the sequence.

There is no harm (or value) in stitching the same file into a sequence twice, other than the wasted computation time. Once a file has been stitched into the sequence, by the definition of the stitching operation, stitching it in again will have no effect.

Output File

File path to write the fully composed USD output file to. This parameter is only evaluated once, at the start of the sequence.

Report Output Files

Prints the paths of files that are written to disk.

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