TOP to CHOP

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Summary
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The TOP to CHOP converts pixels in a TOP image to CHOP channels. It generates one CHOP channel per scanline (row) in the image and per pixel color element (RGBA).

A single pixel, rows of pixels, columns of pixels or rectangular regions can be extracted from the image. It is therefore important to be aware of how many pixels your source image is composed of.

There is an optional input which supplies UV coordinates to sample the image. The input CHOP must contain 2 channels, for U and V. The first channel is always assumed to be U. The channels produced (red, green, blue and alpha) will be exactly as long as the input channel's length, with a value for each UV coordinate.

If you are grabbing pixels from a Depth TOP, you will only get a single channel (the depth). This will be placed in the R channel.

PythonIcon.pngtoptoCHOP_Class


Parameters - Image Page

TOP top - Specify the TOP operator whose image will be sampled.  

Download Type downloadtype - ⊞ - Gives the option for a delayed data download from the GPU, which is much faster and does not stall the render.

  • Immediate (Slow) immediate -
  • Next frame (Fast) nextframe -

Red r - Creates a CHOP channel per scanline with the prefix specified here, starting at 0. For example, the default is "r" in the Red field. If the specified TOP is a horizontal ramp that is 5 lines high, it creates five CHOP channels (r0 - r4) using the values of the red pixels in those scanlines.  

Green g - Creates a CHOP channel per scanline with the prefix specified here, starting at 0. For example, the default is "r" in the Red field. If the specified TOP is a horizontal ramp that is 5 lines high, it creates five CHOP channels (r0 - r4) using the values of the red pixels in those scanlines.  

Blue b - Creates a CHOP channel per scanline with the prefix specified here, starting at 0. For example, the default is "r" in the Red field. If the specified TOP is a horizontal ramp that is 5 lines high, it creates five CHOP channels (r0 - r4) using the values of the red pixels in those scanlines.  

Alpha a - Creates a CHOP channel per scanline with the prefix specified here, starting at 0. For example, the default is "r" in the Red field. If the specified TOP is a horizontal ramp that is 5 lines high, it creates five CHOP channels (r0 - r4) using the values of the red pixels in those scanlines.  

RGBA Units rgbaunit - ⊞ - Scales the output to lie in the range 0-1, 0-255 or 0-65535.

  • 0 to 1 u1 -
  • 0 to 255 u256 -
  • 0 to 65535 u65536 -


Parameters - Crop Page

Crop crop - ⊞ - Specifies what to extract from the image.

  • Pixel (U,V) pixel -
  • Row (U) row -
  • Column (V) col -
  • Rows and Columns block -
  • Full Image full -

UV Units uvunits - ⊞ - Specifies the units for the following 4 parameters. The parameters can use the local variables $NR and $NC for the number of rows and columns.

  • 0 to 1 norm -
  • Pixels pixel -

U Start ustart - Starting point for sampling in U. Values outside the range of the image are determined by the image's extend conditions, in the extend page.  

U End uend - Ending point for sampling in U.  

V Start vstart - Starting point for sampling in V.  

V End vend - Ending point for sampling in V.  

Interpolate interp - ⊞ - Determines the interpolation method when UV sampling with an input CHOP.

  • Nearest Sample nearest -
  • Linear linear -


Parameters - Extend Page

Image Left imageleft - ⊞ - The image extend conditions when sampling the image with U less than 0.

  • Hold hold -
  • Cycle cycle -
  • Mirror mirror -
  • Default Color default -

Image Right imageright - ⊞ - The image extend conditions for U greater than 1.

  • Hold hold -
  • Cycle cycle -
  • Mirror mirror -
  • Default Color default -

Image Bottom imagebottom - ⊞ - The image extend conditions for V less than 0.

  • Hold hold -
  • Cycle cycle -
  • Mirror mirror -
  • Default Color default -

Image Top imagetop - ⊞ - The image extend conditions for V greater than 1.

The extend conditions are:

  • Hold hold - Use the first or last pixel value.
  • Cycle cycle - Loop back to the other side of the image.
  • Mirror mirror - Zig-zag back into the image.
  • Default Color default - Use a default color specified below.

Default Color defcolor - ⊞ - The color to use when outside the bounds of the image, and the Default Color extend condition is set.

  • Red defcolorr -
  • Green defcolorg -
  • Blue defcolorb -
  • Alpha defcolora -


Parameters - Channel Page

Start start - The start position of the channel, expressed in units set by the units menu to the right (samples, frames or seconds). The channel length is determined by the number of pixels in each scanline that is converted into a channel.  

Start Unit startunit -  

Sample Rate rate - The sample rate of the channels, in samples per second.  

Extend Left left - ⊞ - The left extend conditions (before/after range).

  • Hold hold -
  • Slope slope -
  • Cycle cycle -
  • Mirror mirror -
  • Default Value default -

Extend Right right - ⊞ - The right extend conditions (before/after range).

  • Hold hold -
  • Slope slope -
  • Cycle cycle -
  • Mirror mirror -
  • Default Value default -

Default Value defval - The default value for extend conditions.  


Parameters - Common Page

Time Slice timeslice - Turning this on forces the channels to be "Time Sliced". A Time Slice is the time between the last cook frame and the current cook frame.  

Scope scope - To determine which channels get affected, some CHOPs use a Scope string on the Common page.  

Sample Rate Match srselect - ⊞ - Handle cases where multiple input CHOPs' sample rates are different. When Resampling occurs, the curves are interpolated according to the Interpolation Method Option, or "Linear" if the Interpolate Options are not available.

  • Resample At First Input's Rate first - Use rate of first input to resample others.
  • Resample At Maximum Rate max - Resample to the highest sample rate.
  • Resample At Minimum Rate min - Resample to the lowest sample rate.
  • Error If Rates Differ err - Doesn't accept conflicting sample rates.

Export Method exportmethod - ⊞ - This will determine how to connect the CHOP channel to the parameter. Refer to the Export article for more information.

  • DAT Table by Index datindex - Uses the docked DAT table and references the channel via the index of the channel in the CHOP.
  • DAT Table by Name datname - Uses the docked DAT table and references the channel via the name of the channel in the CHOP.
  • Channel Name is Path:Parameter autoname - The channel is the full destination of where to export to, such has geo1/transform1:tx.

Export Root autoexportroot - This path points to the root node where all of the paths that exporting by Channel Name is Path:Parameter are relative to.  

Export Table exporttable - The DAT used to hold the export information when using the DAT Table Export Methods (See above).  


Operator Inputs

  • Input 0 -

TouchDesigner Build:

CHOPs
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An Operator Family that creates, composites and modifies images, and reads/writes images and movies to/from files and the network. TOPs run on the graphics card's GPU.

An Operator Family which operate on Channels (a series of numbers) which are used for animation, audio, mathematics, simulation, logic, UI construction, and many other applications.

The Graphics Processing Unit. This is the high-speed, many-core processor of the graphics card/chip that takes geometry, images and data from the CPU and creates images and processed data.

samples-per-second of a CHOP. Each CHOP in your network has a sample rate, whether it is used or not. The overall timeline has a "frame rate", which is the number of animation frames per second, generally your monitor display frequency.

A Time Slice is the time from the last cook frame to the current cook frame. In CHOPs it is the set of short channels that only contain the CHOP channels' samples between the last and the current cook frame.

A parameter in most CHOPs that restricts which channels of that CHOP will be affected. Normally all channels of a CHOP are affected by the operator.

Exporting is the connection of CHOP channels to parameters of operators. The output of each exporting CHOP is one or more channels, active only while the CHOP Viewer is on. The current value of a channel can be exported to a parameter of any operator, overriding that parameter's value. See Parameter.

An Operator Family that manipulates text strings: multi-line text or tables. Multi-line text is often a command Script, but can be any multi-line text. Tables are rows and columns of cells, each containing a text string.

The location of an operator within the TouchDesigner environment, for example, /geo1/torus1, a node called torus1 in a component called geo1. The path / is called Root. To refer instead to a filesystem folder, directory, disk file or http: address, see Folder.

Parameters in TouchDesigner are an operator's settings (numbers, menus, flags, strings, paths) which the user can alter. Parameters for any operator can be opened by right-clicking on the operator and selecting "Parameters..." A currently selected operator's parameters can be viewed in a Network Editor by pressing the keyboard shortcut 'p'.

TouchDesigner is a hierarchy of components. "root" is the top-most network in the hierarchy. The Path is simply /. A typical path is /project1/moviein1.

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