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This CHOP takes translate, rotate, and/or scale channels and transforms them either using the transform parameters in the CHOP or via other transform channels from its second input. It can be used to:
Change the position and orientation of an object.
Convert a set of transform channels with a certain transform order into an equivalent set of channels with a different transform order.
Change the direction, starting point and scale of motion capture data.
At present, only one transform format exists: the transform defined by
12 channels (
tx ty tz, rx ry rz, sx sy sz) and a transform
The Transform CHOP expects the input channels to have names that end in the above names. Examples are:
geo1:tx geo1:ty geo1:tz geo1:rx ... headtx heaty headtz headrx tx ty tz rx ... (what you would get from a Fetch chop)
The above defines a transformation matrix. This is multiplied by the transform matrix defined from the second input (if present), or on the Transform tab, and output as translate/rotate/etc. channels.
To affect only one set of channels coming into the CHOP, use the Scope parameter. This is used for both the first and second inputs.
This page defines the matrix used to transform the channels. The parameters used to create this matrix are Transform Order, Rotate Order, and the Translate, Rotate, Scale and Pivot parameters. If a second input is present, then only the Transform Order and Rotate Order parameters are used.
If enabled, the transform will be inverted prior to being multiplied with the input.
Currently there is only one output type, the transformed input channels.
The input channels can be pre or post multiplied by the transformation.
This should be set to Post-Multiply when transforming input channels representing transformations, and to Pre-Multiply when transforming input channels representing point positions.
Use Rotation Hint
Supply approximate starting values for the rotation channels.
This page defines what the incoming channels' transform order is assumed to be. Using the incoming channels and the transform order here, a matrix for the incoming channels is built. It is then multiplied by the transformation matrix defined on the Transform tab. Any missing translation, rotation or scale channels will default to zero (or one in the case of scale).
The transform order of the channels from the first input.
The rotation order of the rotations from the first input.
Some of these parameters may not be available on all CHOP nodes.
To determine which channels get affected, some CHOPs have a scope string. Patterns can be used in the scope, for example
* (match all), and
? (match single character).
The following are examples of possible channel name matching options:
Matches a single channel name.
chan3 tx ty tz
Matches four channel names, separated by spaces.
Matches each channel that starts with
Matches each channel that has
foot in it.
? matches a single character.
t? matches two-character channels starting with t.
Matches number ranges giving
[xyz]matches three characters, giving channels
Sample Rate Match
The Sample Rate Match Options handle cases where multiple input CHOPs’ sample rates are different.
Resample At First Input’s Rate
Use rate of first input to resample others.
Resample At Maximum Rate
Resample to highest sample rate.
Resample At Minimum Rate
Resample to the lowest sample rate.
Error if Rates Differ
Does not accept conflicting sample rates.
The units for which time parameters are specified.
For example, you can specify the amount of time a lag should last for in seconds (default), frames (at the Houdini FPS), or samples (in the CHOP’s sample rate).
When you change the Units parameter, it does not convert the existing parameters to the new units.
Time Slicing is a feature which boosts cooking performance and reduces memory usage. Traditionally, CHOPs calculate the channel over its entire frame range. If the channel does need to be evaluated every frame, then cooking the entire range of the channel is unnecessary. It is more efficient to calculate only the fraction of the channel that is needed. This fraction is known as a Time Slice.
Causes the memory consumed by a CHOP to be released after it is cooked and the data passed to the next CHOP.
The Export prefix is prepended to CHOP channel names to determine where to export to.
For example, if the CHOP channel was named
geo1:tx, and the prefix was
/obj, the channel would be exported to
You can leave the Export Prefix blank, but then your CHOP track names need to be absolute paths, such as
Every CHOP has this option. Each CHOP gets a default color assigned for display in the Graph port, but you can override the color in the Common page under Graph Color. There are 36 RGB color combinations in the Palette.
Graph Color Step
When the graph displays the animation curves and a CHOP has two or more channels, this defines the difference in color from one channel to the next, giving a rainbow spectrum of colors.
The current index.