The Foundry Nuke's Reformat node issue

Question

I wanted to track my footage and add CG elements to it as part of my nuke project. For that purpose, I undistorted the footage & wrote it down to disk for faster processing. However, when I tried to re-distort the written footage (as shown in attached pic), its not giving me original footage. I found that the Reformat5 and Reformat7 are not giving me the same bounding box dimensions even though both the nodes are the same.

My original footage size is 1920*1080. After undistorting, it becomes 1928*1085.

Hence I put a Reformat4 node with the dimensions 1928*1085 and wrote it down to disk. On the left side, I again put reformat node to resize the undistorted footage back to 1920*1080 with bounding box of size 1928*1085 preserved so as to perform lens distortion to get back my original footage.

Its working fine on left side but if I do the same thing on my written footage, the bounding box dimensions are not same.

Reformat7 gives bounding box of size 1924*1083 instead of 1928*1085. What am I missing here ? I searched the web but I cant find any solution. Please throw some light on this issue.

my nuke script is as follows :

set cut_paste_input [stack 0]
version 10.0 v3
push $cut_paste_input
LensDistortion {
 serializeKnob ""
 serialiseKnob "22 serialization::archive 9 0 0 0 0 0 0 0 0 0 0 0 0"
 distortion1 -0.007498324849
 distortion2 0.0008674863493
 distortionCenter {-0.002916968195 -0.001372990897}
 invertDistortion true
 cardScale {1.006676197 1.006676197 1}
 a 0.001508030226
 b -0.006750627421
 c -0.002457624534
 analysisStart 1
 analysisStop 329
 name LensDistortion2
 selected true
 xpos -451
 ypos 651
}
Reformat {
 format "1928 1085 0 0 1928 1085 1 undistortedFormat2"
 resize none
 name Reformat4
 selected true
 xpos -451
 ypos 684
}
set N6eafc00 [stack 0]
Reformat {
 resize none
 pbb true
 name Reformat5
 selected true
 xpos -451
 ypos 745
}
LensDistortion {
 serializeKnob ""
 serialiseKnob "22 serialization::archive 9 0 0 0 0 0 0 0 0 0 0 0 0"
 distortion1 -0.007498324849
 distortion2 0.0008674863493
 distortionCenter {-0.002916968195 -0.001372990897}
 cardScale {0.9934444427 0.9934444427 1}
 a -0.0004114751064
 b 0.004895505495
 c 0.002436506096
 analysisStart 1
 analysisStop 329
 name LensDistortion3
 selected true
 xpos -451
 ypos 782
}
push $N6eafc00
Write {
 file F:/Assignments/Nuke/CGComp/footages/undistortedFootage1080p/undistortedFootage1080p.####.exr
 file_type exr
 name Write7
 selected true
 xpos -269
 ypos 684
}
Reformat {
 resize none
 pbb true
 name Reformat7
 selected true
 xpos -269
 ypos 747
}
LensDistortion {
 serializeKnob ""
 serialiseKnob "22 serialization::archive 9 0 0 0 0 0 0 0 0 0 0 0 0"
 distortion1 -0.007498324849
 distortion2 0.0008674863493
 distortionCenter {-0.002916968195 -0.001372990897}
 cardScale {0.9934444427 0.9934444427 1}
 a -0.0004114751064
 b 0.004895505495
 c 0.002436506096
 analysisStart 1
 analysisStop 329
 name LensDistortion5
 selected true
 xpos -269
 ypos 783
}

Andy Jazz · Answer 1 · 2017-10-07T14:53:02.310

2

You need to use CopyBBox node for solving your issue. This Python command creates connected CopyBBox node:

import nuke
nuke.createNode("CopyBBox")

or you can create a disconnected one from other nodes with this command:

nuke.nodes.CopyBBox()

CopyBBox copies the bounding box from the A input onto the B stream. The bounding box defines the area of the frame that Nuke sees as having valid image data. The larger the bounding box is, the longer it takes Nuke to process and render the images.

Some NUKE operations, such as a Merge, Blur, or LensDistortion can cause an expansion or decrease of the bounding box area because NUKE does not know that the extra area is going to be black or another constant color. Often, you can fix this by copying the bounding box from one of the inputs to the resulting image, thus cutting off the extra area.

nuke.nodes.Transform(scale=1.005, filter="Mitchell")

And if you have a "Stretched pixels effect" at right margin, use scale=1.005 parameter in Transform node (right after your LensDistortion5 node). Also, don't forget to use filtering algorithm.

edited Oct 07 '17 at 14:53

answered Oct 07 '17 at 13:31

Andy Jazz

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Sorry but I don't see how adding CopyBBox after Lens distortion will rectify the issue. I tried your solution but still the right hand side is not working. I am getting artifacts around edges. – akshay7692 Oct 07 '17 at 13:43
I tried to add copyBbox after reformat7 to provide correct bounding box as input to LD5 but the output bbox of LD5 is still less than 1920*1080 :( – akshay7692 Oct 07 '17 at 13:46
Usually, compositing artists use CopyBBox in the end of a script (right before the final Write node). I've got BB 1920x1080 as you need. In your script. – Andy Jazz Oct 07 '17 at 13:49
Check one more time the "Output Format" in all Reformat nodes. – Andy Jazz Oct 07 '17 at 13:53
The LD5 gives my a bbox of 1918*1082 (instead of 1922*1084 as in LD3) , so some outer pixels are lost. Adding copyBbox at end gives me correct bbox but the lost pixels are still gone. – akshay7692 Oct 07 '17 at 13:54
Give me a source picture. – Andy Jazz Oct 07 '17 at 13:55
I think as long as Reformat7 doesnt output correct bbox, LD5 output wont be same as LD3. What do you think? – akshay7692 Oct 07 '17 at 13:56
Try in Reformat7 "type" dropdown menu ("to format" vs "to box"). – Andy Jazz Oct 07 '17 at 13:57
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/156163/discussion-between-akshay7692-and-andy). – akshay7692 Oct 07 '17 at 13:58

The Foundry Nuke's Reformat node issue

1 Answers1