Using PanoTools projects within Natron
Those are preliminary notes on using PanoTools or Hugin projects from within Natron.
Creating a PanoTools (pto) project
Using the Hugin GUI
Using command-line tools
Full details on using command-line tools are given in the Panorama scripting in a nutshell documentation.
On macOS, if Hugin was installed using homebrew, the tools are available in various directories, and they can be added to the PATH using:
Here is an example of running the panorama tools from a set of JPEG
images (with suffix
.jpg) placed in the current directory to
generate e perspective panorama (other options are described in the
pto_gen -o project.pto *.JPG
cpfind --multirow -o project.pto project.pto
celeste_standalone -i project.pto -o project.pto
cpclean -v --output project.pto project.pto
autooptimiser -a -l -s -m -o project.pto project.pto
nona -m TIFF_m -o project project.pto
enblend --save-masks -o panorama.tif project*.tif
The result is:
project.ptofile, which is the Hugin project itself
project*.tifimages, which are images warped to the reference projection.
mask-*.tifimages, which are masks generated by
panorama.tifimage, which is the final panorama.
Using Hugin/PanoTools parameters in Natron
This file can be viewed and edited in any text editor.
The project size, or format, should be set to the panorama size, which
is given in pixels on the
p line (at the start of the file).
The distortion correction parameters for the input images are given in
i lines (one for each image).
The values for the
parameters should be entered in a LensDistortion node, with
model=PanoTools and Direction/
placed after the Read node for each input image or video. The script
name for these values are
Note that if all images share the same distortion parameters (this is
a=0 b=0 c=0 d=0 e=0 g=0 t=0 on the
i line), the
LensDistortion node can be cloned in Natron (right-click on node,
Edit, Clone Nodes).
The projection (which can be performed by the Nona tool) can be done using Card3D nodes placed after each LensDistortion node.
Each Card3D node must have its Transform Order/
set to STR, and the Rotation Order/
cardRotOrder should be left to
the default value (ZXY). Be careful, these are neither the Axis nor the
Cam Transform Order, which are in the two first groups of the
Set the Output Format to Project.
y values from the
i line are roll, yaw,
pitch angles. Their values should be put in the Rotate parameter of
the Card3D (script name is
cardRotate), using the following
cardRotate.x = p,
cardRotate.y = -y,
cardRotate.z = -r.
v value from the
i line corresponds to the horizontal field
of view, and has to be converted to an aperture value. The Lens-In
lensInHAperture param should be set to
2*tan(v*pi/360). This expression can be directly typed in the value
v replaced by the actual value from the corresponding
i line of the
Setup all the Card3D nodes for each input image that way.
In Natron 2, the camera used by the Card3D node is set in the Cam group at the top of the parameters list.
In the Card3D node for the first image, unfold this group, and unfold the Cam Projection group.
v value on the
p line (usually at the top of the
file) gives the horizontal field of view of the output panorama.
Set the Focal Length/
camfocal to 1., and set the Horiz.
its actual value.
You can then copy these two parameters to all the Card3D nodes, or - even better - link these parameters, so that the output camera for the panorama can then be modified: Right-click on the parameter from the first Card3D, Copy Link, then right-click on the same parameter of every other Card3D node, Paste Link.
If you intend to modify the camera orientation later, you can also link
the same way the Rotate/
camRotate parameter (those for the camera,
not the card).
Note that when the Natron Card3D node is used in Nuke (where it appears as Card3DOFX), the node has an external Cam input, to which a Camera node may be connected. There may be a similar concept in future versions of Natron.
Building the panorama in Natron
First sketch: overlap the images
Make sure that the Output Components parameter in all readers is set to RGBA, so that images have a transparent value outside of their domain.
Now, connect the outpput of the first Card3D to the B input of a Merge node, connect the secont to the A input, the third to the A2 input, etc…
The output of the Merge node should show a first panorama, obtained by overlapping all images.
Drawing the masks
Add a Roto node after each LensDistortion, before each Card3D.
Only leave connected the A and B inputs to the Merge node to the two first Card3D nodes.
Check Premultiply in each Roto node, check that only the A channel is affected by Roto in its parameters, and start editing the roto mask on the second image, for which the LensDistortion output is connected to the A input of the Merge, while viewing the output of the Merge.
Set the compositing operator of each roto shape to “min” instead of “over”, so that the original image alpha gets masked by the roto shape.
Do not forget to add feather, especially in the overlap area.
Then, reconnect the A2 input to the third Card3D, and start editing its roto mask, always in “min” compositing mode.
Do the same with A3, A4, etc… and you should end up with a full panorama.
Re on the
i line encode a
color response curve (EMoR). See
EMoRParamsin the hugin source
Exposure and color
Eev encodes the exposure, see
ExposureValue in the hugin source
Eb encode the red and blue multipliers, see
WhiteBalanceBlue in the hugin source code.
Va is always 1, see
VigCorrMode in the hugin source code.
Vd encode the degree 2, 4 and 6 coefficients for
vignette correction, see
RadialVigCorrCoeff in the hugin source
Vy encode the vignetting center shift, see
RadialVigCorrCenterShift in the hugin source code.
importing enblend masks, using them as roto masks
executing enblend externally (using RunScript maybe?)