<< Click to Display Table of Contents >> Navigation:  Nodes > Tasks > VR Tools > Stitch Auto Calibrate

 

Purpose

 

To apply automatic calibration of the lenses of an VR rig before stitching the cameras, in order to automate VR production. This node will get a Mistika  rnd  containing images to be stitched (and a stitch effect) and it will calculate the lenses parameters that better describe the images, including the focal length, lens distortion, lenses orientation, and lens center. Then it will output an rnd containing the new values.

In the Mistika VR product, it is equivalent of executing Stitch -> Autoc calibrate .

This node implies a much more exhaustive analysis than the stitch refiner node, so it is also much slower. If the lenses of the camera rig are not changing between shots then it is more efficient to only use auto calibrate to create a first .rnd preset describing the lense geometries and then use Stitch Refiner for further shots of the same rig.

When this node is considered necessary (that is, if you do not have a good stitching preset describing your camera rig)  it should be applied as the first step of the stitching process, because the lenses description that it provides will need to be used by any posterior stitching tools (such as StabilizeVR, Stitch Align Mesh , etc)

For this workflow, the first step would be to use Mistika VR or Mistika Boutique to prepare a .rnd file representing a basic stitching example (with some sample footage). Then  in Mistika Workflows load the rnd into a RNDFile node and connect it to a Stitch Auto Calibrate node to apply fine adjustments and then connect it it to the MistikaRender node for final rendering.

You may also want to load successive bunches of camera rushes automatically, for which you can use the VR Input Bunches effect.  In that case, the said workflow could be something like this:  

Folder (or Watcher) containing incoming camera footage-> VR Input Bunches -> RNDfile (rnd containing your VR preset) -> Stitch Auto Calibrate-> MistikaRender

Here it is a  video tutorial for this workflow: https://youtu.be/JiaBniQOcxk?t=98

Inputs

 

rnd:  A .rnd file containing the stitching effect applied by default.  (the initial .rnd files are normally created in Mistika VR or Mistika Boutique products. Then used as templates in Mistika Workflows by nodes supporting them)

 

Outputs

 

rnd: The .rnd file with the lenses calibration applied.

 

 

Standard properties

 

Object Name

Color

Bypass

Lock

 

Node specific properties

 

Mode: 180 or 360. Here you need to specify if the VR camera rig cover 360 degree or 180 degree.

 

Focal Length, Lens Distortion, Orientation, Lens Center:  Lenses parameters to be calibrated.

 

Points: Mistika will insert many analysis points in strategical locations of the images to be used for the calculations. This property specifies how many points will be analyzed. increasing points can improve precision in some cases, but the processing can be much slower.

 

 

Developer reference (API Rest - node/StitchAutoCalibrate/property/[Property ID])