Vision callback functions

Child scripts, or customization scripts can include a vision callback function (which is one of many system callback functions), when associated with a vision sensor. When present for a given vision sensor, then the system will call the callback function everytime a new image was acquired or applied, allowing the user to perform image processing. This is the case with following API functions: sim.handleVisionSensor, sim.checkVisionSensor, sim.checkVisionSensorEx, and sim.setVisionSensorImg.

Some conditions apply as to the location of the vision callback function: if a vision callback function is present in a child script as well as in a customization script, both attached to the vision sensor, then the child script will be called first, and the customization script second.

Following represents an empty vision callback function:

function sysCall_vision(inData) -- We have: -- inData.handle : the handle of the vision sensor. -- inData.resolution : the x/y resolution of the vision sensor -- inData.clippingPlanes : the near and far clipping planes of the vision sensor -- inData.viewAngle : the view angle of the vision sensor (if in persp. proj. mode) -- inData.orthoSize : the ortho size of the vision sensor (if in orth. proj. mode) -- inData.perspectiveOperation : true if the sensor is in persp. proj. mode local outData={} outData.trigger=false -- true if the sensor should trigger outData.packedPackets={} -- a table of packed packets. Can be accessed via e.g. sim.readVisionSensor return outData end

Image processing can be performed by using various API functions. The vision plugin exports a few very simple image processing functions. Many more image processing functions are supported via the image plugin (OpenCV wrapper).

Following represents a simple edge detection vision callback function, that triggers and returns a packet of data (based on the vision plugin functions):

function sysCall_vision(inData) simVision.sensorImgToWorkImg(inData.handle) simVision.edgeDetectionOnWorkImg(inData.handle,0.1) simVision.workImgToSensorImg(inData.handle) local outData={} outData.trigger=true local packetData={1.0,42.123,129.3} outData.packedPackets={sim.packFloatTable(packetData)} return outData end

Following represents a vision callback function, that draws a circle onto the acquired image (based on the image plugin functions):

function sysCall_vision(inData) local imgHandle=simIM.readFromVisionSensor(inData.handle) local center={inData.resolution[1]/2,inData.resolution[2]/2} local radius=(inData.resolution[1]+inData.resolution[2])/8,center,radius,{255,0,255},4) simIM.writeToVisionSensor(imgHandle,inData.handle) simIM.destroy(imgHandle) end

In Python, a vision callback function can only be implemented via a non-threaded script, and it should be explicitly activated with a luaExec command:

#python #luaExec additionalFuncs={'sysCall_vision'} def sysCall_vision(inData): pass