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  2. Blob Track TOP

    Blob Track TOP

    Summary

    The Blob Track TOP is implemented using OpenCV.

    To get the results of the Blob Track TOP, attach an Info DAT or Info CHOP to it. The Info reports the current blob IDs, coordinates and sizes in pixels. The blob ID increases for every new blob that is detected.

    It converts the incoming image to monochrome (since it operates on an single color channel), but to better prepare the image, preceed it with a Monochrome TOP followed by a Luma Level TOP, and adjust Black Level, Brightness and Gamma.

    Typical usage is connecting a video source (such as Video Device In TOP to the Blob Track TOP).

    NOTE: can track an unlimited number of blobs in Pro and Commercial, and up to 2 blobs in the Non-Commercial version of TouchDesigner.

    See also Blob Track CHOP

    PythonIcon.pngblobtrackTOP_Class


    Usage

    There are two workflows with the Blob Track TOP.

    SimpleBlobDetector

    SimpleBlobDetector is a blob detection algorithm in OpenCV. This method will automatically be used if only the first input is connected. SimpleBlobDetector has the benefit of not requiring a known background to detect blobs but only returns blobs as a position and radius, meaning that all blobs rectangles will be square. The SimpleBlobDetector can also be quite slow so lowering the input resolution is often necessary. Generally this method should only be used if the background is not known.


    Background Subtraction

    Background subtraction will automatically be used if there is a second input connected. Background subtraction is less dynamic and requires a known background to function but it offers a massive performance improvement over SimpleBlobDetector, and unlike with SimpleBlobDetector the blob rectangles using this method are not restricted to squares only. The background subtraction method will create a binary image from the first and second input (based off the threshold parameter) and then use OpenCV to find contours and convert those to rectangles.


    Parameters - Blob Track Page

    Reset reset - Resets all tracking data and learned background data while this parameter is On.

    Reset Pulse resetpulse - Instantly resets all tracking data and learned background data.

    Mono Source monosource - ⊞ - Blob tracking is done using a single channel. This menu controls what single channel is used to detect blobs.
    • Luminance luminance -
    • Red red -
    • Green green -
    • Blue blue -
    • Alpha alpha -
    • RGB Average rgbaverage -
    • RGBA Average average -

    Draw Blob Bounds drawblobs - Draws rectangles on the TOP image that shows where the tracked blobs are.

    Blob Bound Color blobcolor - ⊞ - Determines the color of the rectangles that are drawn to show the blobs.
    • Red blobcolorr -
    • Green blobcolorg -
    • Blue blobcolorb -
    Threshold threshold - Threshold used to create the binary texture when using background subtraction. It is the threshold of the difference between the background texture and the input texture.


    Parameters - Constraints Page

    Minimum Blob Size minblobsize - Blobs must be at least this big to be tracked.

    Maximum Blob Size maxblobsize - Blobs larger than this will not be tracked.

    Maximum Move Distance maxmovedistance - The maximum distance a blob can move in one frame and still be considered to the same blob (maintain the same ID).

    Delete Nearby Blobs deletenearby - Sometimes (depending on the tracking method) duplicate blobs may be created. This feature allows you to delete blobs that are too close to each other.

    Minimum Distance deletedist - When deleting nearby blobs, blobs will be deleted if they are within this number of pixels of each other. The smaller blob will be deleted.

    Delete Area Tolerance deletenearbytol - Along with the distance, the area of the two blobs can be compared. If this parameter is 1, than the area is ignored. As this parameter gets smaller only blobs that have a significant size difference (between the two blobs being compared) will be deleted.

    Delete Overlapping Blobs deleteoverlap - Deletes blobs that are overlapping.

    Delete Overlap Tolerance deleteoverlaptol - If this parameter is 1 then only blobs that are completely overlapped will be deleted. As this value gets smaller less and less overlap is needed for a blob to get deleted.


    Parameters - Revival Page

    Revive Blobs reviveblobs - When enabled, will revive lost blobs (ie. same ID) if they satisfy all the below parameters

    Revive Time revivetime - The time (in seconds) threshold for reviving a lost blob. If a blob has been lost for longer than revive time, it will not be revived and is considered expired.

    Revive Area Difference revivearea - The area difference threshold for the new blob and the lost blob.

    Revive Distance revivedistance - The distance threshold between the new blob and the lost blob.

    Include Lost Blobs in Table includelost - When enabled, lost blobs will be included in the Blob Track TOP's Info DAT table.

    Include Expired Blobs in Table includeexpired - When enabled, expired blobs (ie. blobs that have no chance of revival) will be included in the Blob Track TOP's Info DAT table.

    Expired Time expiredtime - Time in seconds for blobs to remain in the Info DAT table after expiring.


    Parameters - Common Page

    Output Resolution outputresolution - ⊞ - quickly change the resolution of the TOP's data.
    • Use Input useinput - Uses the input's resolution.
    • Eighth eighth - Multiply the input's resolution by that amount.
    • Quarter quarter - Multiply the input's resolution by that amount.
    • Half half - Multiply the input's resolution by that amount.
    • 2X 2x - Multiply the input's resolution by that amount.
    • 4X 4x - Multiply the input's resolution by that amount.
    • 8X 8x - Multiply the input's resolution by that amount.
    • Fit Resolution fit - Fits the width and height to the resolution given below, while maintaining the aspect ratio.
    • Limit Resolution limit - The width and height are limited to the resolution given below. If one of the dimensions exceeds the given resolution, the width and height will be reduced to fit inside the given limits while maintaining the aspect ratio.
    • Custom Resolution custom - Enables the Resolution parameter below, giving direct control over width and height.
    Resolution resolution - ⊞ - Enabled only when the Resolution parameter is set to Custom Resolution. Some Generators like Constant and Ramp do not use inputs and only use this field to determine their size. The drop down menu on the right provides some commonly used resolutions.
    • W resolutionw -
    • H resolutionh -
    Resolution Menu resmenu - A drop-down menu with some commonly used resolutions.

    Use Global Res Multiplier resmult - Uses the Global Resolution Multiplier found in Edit>Preferences>TOPs. This multiplies all the TOPs resolutions by the set amount. This is handy when working on computers with different hardware specifications. If a project is designed on a desktop workstation with lots of graphics memory, a user on a laptop with only 64MB VRAM can set the Global Resolution Multiplier to a value of half or quarter so it runs at an acceptable speed. By checking this checkbox on, this TOP is affected by the global multiplier.

    Output Aspect outputaspect - ⊞ - Sets the image aspect ratio allowing any textures to be viewed in any size. Watch for unexpected results when compositing TOPs with different aspect ratios. (You can define images with non-square pixels using xres, yres, aspectx, aspecty where xres/yres != aspectx/aspecty.)
    • Use Input useinput - Uses the input's aspect ratio.
    • Resolution resolution - Uses the aspect of the image's defined resolution (ie 512x256 would be 2:1), whereby each pixel is square.
    • Custom Aspect custom - Lets you explicitly define a custom aspect ratio in the Aspect parameter below.
    Aspect aspect - ⊞ - Use when Output Aspect parameter is set to Custom Aspect.
    • Aspect1 aspect1 -
    • Aspect2 aspect2 -
    Aspect Menu armenu - A drop-down menu with some commonly used aspect ratios.

    Input Smoothness inputfiltertype - ⊞ - This controls pixel filtering on the input image of the TOP.
    • Nearest Pixel nearest - Uses nearest pixel or accurate image representation. Images will look jaggy when viewing at any zoom level other than Native Resolution.
    • Interpolate Pixels linear - Uses linear filtering between pixels. This is how you get TOP images in viewers to look good at various zoom levels, especially useful when using any Fill Viewer setting other than Native Resolution.
    • Mipmap Pixels mipmap - Uses mipmap filtering when scaling images. This can be used to reduce artifacts and sparkling in moving/scaling images that have lots of detail.
    Fill Viewer fillmode - ⊞ - Determine how the TOP image is displayed in the viewer.

    NOTE:To get an understanding of how TOPs work with images, you will want to set this to Native Resolution as you lay down TOPs when starting out. This will let you see what is actually happening without any automatic viewer resizing.

    • Use Input useinput - Uses the same Fill Viewer settings as it's input.
    • Fill fill - Stretches the image to fit the edges of the viewer.
    • Fit Horizontal width - Stretches image to fit viewer horizontally.
    • Fit Vertical height - Stretches image to fit viewer vertically.
    • Fit Best best - Stretches or squashes image so no part of image is cropped.
    • Fit Outside outside - Stretches or squashes image so image fills viewer while constraining it's proportions. This often leads to part of image getting cropped by viewer.
    • Native Resolution nativeres - Displays the native resolution of the image in the viewer.
    Viewer Smoothness filtertype - ⊞ - This controls pixel filtering in the viewers.
    • Nearest Pixel nearest - Uses nearest pixel or accurate image representation. Images will look jaggy when viewing at any zoom level other than Native Resolution.
    • Interpolate Pixels linear - Uses linear filtering between pixels. Use this to get TOP images in viewers to look good at various zoom levels, especially useful when using any Fill Viewer setting other than Native Resolution.
    • Mipmap Pixels mipmap - Uses mipmap filtering when scaling images. This can be used to reduce artifacts and sparkling in moving/scaling images that have lots of detail.
    Passes npasses - Duplicates the operation of the TOP the specified number of times. Making this larger than 1 is essentially the same as taking the output from each pass, and passing it into the first input of the node and repeating the process. Other inputs and parameters remain the same for each pass.

    Channel Mask chanmask - Allows you to choose which channels (R, G, B, or A) the TOP will operate on. All channels are selected by default.

    Pixel Format format - ⊞ - Format used to store data for each channel in the image (ie. R, G, B, and A). Refer to Pixel Formats for more information.
    • Use Input useinput - Uses the input's pixel format.
    • 8-bit fixed (RGBA) rgba8fixed - Uses 8-bit integer values for each channel.
    • sRGB 8-bit fixed (RGBA) srgba8fixed - Uses 8-bit integer values for each channel and stores color in sRGB colorspace.
    • 16-bit float (RGBA) rgba16float - Uses 16-bits per color channel, 64-bits per pixel.
    • 32-bit float (RGBA) rgba32float - Uses 32-bits per color channel, 128-bits per pixels.
    • 10-bit RGB, 2-bit Alpha, fixed (RGBA) rgb10a2fixed - Uses 10-bits per color channel and 2-bits for alpha, 32-bits total per pixel.
    • 16-bit fixed (RGBA) rgba16fixed - Uses 16-bits per color channel, 64-bits total per pixel.
    • 11-bit float (RGB), Positive Values Only rgba11float - A RGB floating point format that has 11 bits for the Red and Green channels, and 10-bits for the Blue Channel, 32-bits total per pixel (therefore the same memory usage as 8-bit RGBA). The Alpha channel in this format will always be 1. Values can go above one, but can't be negative. ie. the range is [0, infinite).
    • 16-bit float (RGB) rgb16float -
    • 32-bit float (RGB) rgb32float -
    • 8-bit fixed (Mono) mono8fixed - Single channel, where RGB will all have the same value, and Alpha will be 1.0. 8-bits per pixel.
    • 16-bit fixed (Mono) mono16fixed - Single channel, where RGB will all have the same value, and Alpha will be 1.0. 16-bits per pixel.
    • 16-bit float (Mono) mono16float - Single channel, where RGB will all have the same value, and Alpha will be 1.0. 16-bits per pixel.
    • 32-bit float (Mono) mono32float - Single channel, where RGB will all have the same value, and Alpha will be 1.0. 32-bits per pixel.
    • 8-bit fixed (RG) rg8fixed - A 2 channel format, R and G have values, while B is 0 always and Alpha is 1.0. 8-bits per channel, 16-bits total per pixel.
    • 16-bit fixed (RG) rg16fixed - A 2 channel format, R and G have values, while B is 0 always and Alpha is 1.0. 16-bits per channel, 32-bits total per pixel.
    • 16-bit float (RG) rg16float - A 2 channel format, R and G have values, while B is 0 always and Alpha is 1.0. 16-bits per channel, 32-bits total per pixel.
    • 32-bit float (RG) rg32float - A 2 channel format, R and G have values, while B is 0 always and Alpha is 1.0. 32-bits per channel, 64-bits total per pixel.
    • 8-bit fixed (A) a8fixed - An Alpha only format that has 8-bits per channel, 8-bits per pixel.
    • 16-bit fixed (A) a16fixed - An Alpha only format that has 16-bits per channel, 16-bits per pixel.
    • 16-bit float (A) a16float - An Alpha only format that has 16-bits per channel, 16-bits per pixel.
    • 32-bit float (A) a32float - An Alpha only format that has 32-bits per channel, 32-bits per pixel.
    • 8-bit fixed (Mono+Alpha) monoalpha8fixed - A 2 channel format, one value for RGB and one value for Alpha. 8-bits per channel, 16-bits per pixel.
    • 16-bit fixed (Mono+Alpha) monoalpha16fixed - A 2 channel format, one value for RGB and one value for Alpha. 16-bits per channel, 32-bits per pixel.
    • 16-bit float (Mono+Alpha) monoalpha16float - A 2 channel format, one value for RGB and one value for Alpha. 16-bits per channel, 32-bits per pixel.
    • 32-bit float (Mono+Alpha) monoalpha32float - A 2 channel format, one value for RGB and one value for Alpha. 32-bits per channel, 64-bits per pixel.


    Operator Inputs

    • Input 0: -


    Info CHOP Channels

    Extra Information for the Blob Track TOP can be accessed via an Info CHOP.

    Specific Blob Track TOP Info Channels

    • num_blobs -

    Common TOP Info Channels

    • resx - Horizontal resolution of the TOP in pixels.
    • resy - Vertical resolution of the TOP in pixels.
    • aspectx - Horizontal aspect of the TOP.
    • aspecty - Vertical aspect of the TOP.
    • depth - Depth of 2D or 3D array if this TOP contains a 2D or 3D texture array.
    • gpu_memory_used - Total amount of texture memory used by this TOP.

    Common Operator Info Channels

    • total_cooks - Number of times the operator has cooked since the process started.
    • cook_time - Duration of the last cook in milliseconds.
    • cook_frame - Frame number when this operator was last cooked relative to the component timeline.
    • cook_abs_frame - Frame number when this operator was last cooked relative to the absolute time.
    • cook_start_time - Time in milliseconds at which the operator started cooking in the frame it was cooked.
    • cook_end_time - Time in milliseconds at which the operator finished cooking in the frame it was cooked.
    • cooked_this_frame - 1 if operator was cooked this frame.
    • warnings - Number of warnings in this operator if any.
    • errors - Number of errors in this operator if any.


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