ID 150238 - Banding appears on Roto/Rotopaint Motionblur when used in high frame ranges

set cut_paste_input [stack 0]version 11.3 v1push $cut_paste_inputRoto { output alpha curves {{{v x3f99999a}  {f 0}  {n   {layer Root    {f 2097664}    {t x44800000 x44100000}    {a pt1x 0 pt1y 0 pt2x 0 pt2y 0 pt3x 0 pt3y 0 pt4x 0 pt4y 0 ptex00 0 ptex01 0 ptex02 0 ptex03 0 ptex10 0 ptex11 0 ptex12 0 ptex13 0 ptex20 0 ptex21 0 ptex22 0 ptex23 0 ptex30 0 ptex31 0 ptex32 0 ptex33 0 ptof1x 0 ptof1y 0 ptof2x 0 ptof2y 0 ptof3x 0 ptof3y 0 ptof4x 0 ptof4y 0 pterr 0 ptrefset 0 ptmot x40800000 ptref 0}    {curvegroup Bezier1 512 bezier     {{cc       {f 8192}       {p        {{{x49e2db58 x40000000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}      {{x49e2db58 xc0800000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}}        {{{x49e2db58 x449e4000 -}       {x49e2db58 x43bfaaac -}       {x49e2db70 x446b84bf x43204444 1 x43204444 1}       {x49e2db88 x44a81dde x42f297b0 1 0 1}}      {{x49e2db58 x44778000 -}       {x49e2db58 x44a79dde -}       {x49e2db70 x446de89c xc24467b0 1 xc24467b0 1}       {x49e2db88 x4461a221 -}}}        {{{x49e2db58 xc0000000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}      {{x49e2db58 x40800000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}}        {{{x49e2db58 xc2c40000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}      {{x49e2db58 x42cc0000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}}        {{{x49e2db58 x44830000 -}       {x49e2db58 x4323332d -}       {x49e2db70 x44347c36 x43204446 1 x43204446 1}       {x49e2db88 x448c999a x42f297b2 1 0 1}}      {{x49e2db58 x44170000 -}       {x49e2db58 x446ebbbc -}       {x49e2db70 x440d689c xc24467b0 1 xc24467b0 1}       {x49e2db88 x44012221 -}}}        {{{x49e2db58 x42c40000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88 x42c3fff0 xb8800000 1 0 1}}      {{x49e2db58 xc2cc0000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}}        {{{x49e2db58 xc2980000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}      {{x49e2db58 xc2f80000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}}        {{{x49e2db58 x44c30000 -}       {x49e2db58 x4428cccc -}       {x49e2db70 x449a3e1a x43204444 1 x43204444 1}       {x49e2db88 x44cc9999 x42f297b4 1 0 1}}      {{x49e2db58 x43a10000 -}       {x49e2db58 x44283bbc -}       {x49e2db70 x438dd139 xc24467b0 1 xc24467b0 1}       {x49e2db88 x436a8886 -}}}        {{{x49e2db58 x42980000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}      {{x49e2db58 x42f80000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}}        {{{x49e2db58 x42f00000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}      {{x49e2db58 xc3180000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}}        {{{x49e2db58 x44d3c000 -}       {x49e2db58 x444a4ccc -}       {x49e2db70 x44aafe1a x43204444 1 x43204444 1}       {x49e2db88 x44dd5999 x42f297b4 1 0 1}}      {{x49e2db58 x44420000 -}       {x49e2db58 x448cddde -}       {x49e2db70 x4438689c xc24467b0 1 xc24467b0 1}       {x49e2db88 x442c2221 -}}}        {{{x49e2db58 xc2f00000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}      {{x49e2db58 x43180000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}}}}      {cc       {f 8192}       {p        {{{x49e2db58 x40000000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}      {{x49e2db58 xc0800000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}}        {{{x49e2db58 0 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}      {{x49e2db58 0 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}}        {{{x49e2db58 xc0000000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}      {{x49e2db58 x40800000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}}        {{{x49e2db58 xc2c40000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}      {{x49e2db58 x42cc0000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}}        {{{x49e2db58 0 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}      {{x49e2db58 0 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}}        {{{x49e2db58 x42c40000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88 x42c3fff0 xb8800000 1 0 1}}      {{x49e2db58 xc2cc0000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}}        {{{x49e2db58 xc2980000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}      {{x49e2db58 xc2f80000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}}        {{{x49e2db58 0 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}      {{x49e2db58 0 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}}        {{{x49e2db58 x42980000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}      {{x49e2db58 x42f80000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}}        {{{x49e2db58 x42f00000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}      {{x49e2db58 xc3180000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}}        {{{x49e2db58 0 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}      {{x49e2db58 0 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}}        {{{x49e2db58 xc2f00000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}      {{x49e2db58 x43180000 -}       {x49e2db58}       {x49e2db70}       {x49e2db88}}}}}}     {t   {{x49e2db50 x44ae0000}}   {{x49e2db50 x44284000}}   {{x49e2db50 0}}   {{x49e2db50 0}}   {{x49e2db50 0}}   {{x49e2db50 0}}   {{x49e2db50 0}}   {{x49e2db50 0}}   {{x49e2db50 0}}   {{x49e2db50 1}}  1   {{x49e2db50 1}}   {{x49e2db50 0}}   {{x49e2db50 0}}   {{x49e2db50 0}}   {{x49e2db50 0}}   {{x49e2db50 0}}   {{x49e2db50 0}}   {{x49e2db50 0}}   {{x49e2db50 1}}   {{x49e2db50 0}}   {{x49e2db50 0}}   {{x49e2db50 0}}   {{x49e2db50 0}}   {{x49e2db50 1}}   {{x49e2db50 0}}   {{x49e2db50 0}}   {{x49e2db50 0}}   {{x49e2db50 0}}   {{x49e2db50 1}}   {{x49e2db50 0}}   {{x49e2db50 0}}   {{x49e2db50 0}}   {{x49e2db50 0}}   {{x49e2db50 1}}}     {a mbo 1 osw x41200000 osf 0 str 1 spx x44800000 spy x44100000 sb 1 ltn x49e2db50 ltm x49e2db50 tt x40800000}}}}}} toolbox {selectAll {  { selectAll str 1 ssx 1 ssy 1 sf 1 }  { createBezier str 1 ssx 1 ssy 1 sf 1 sb 1 tt 4 }  { createBezierCusped str 1 ssx 1 ssy 1 sf 1 sb 1 tt 5 }  { createBSpline str 1 ssx 1 ssy 1 sf 1 sb 1 }  { createEllipse str 1 ssx 1 ssy 1 sf 1 sb 1 }  { createRectangle str 1 ssx 1 ssy 1 sf 1 sb 1 }  { createRectangleCusped str 1 ssx 1 ssy 1 sf 1 sb 1 }  { brush str 1 ssx 1 ssy 1 sf 1 sb 1 }  { eraser src 2 str 1 ssx 1 ssy 1 sf 1 sb 1 }  { clone src 1 str 1 ssx 1 ssy 1 sf 1 sb 1 }  { reveal src 3 str 1 ssx 1 ssy 1 sf 1 sb 1 }  { dodge src 1 str 1 ssx 1 ssy 1 sf 1 sb 1 }  { burn src 1 str 1 ssx 1 ssy 1 sf 1 sb 1 }  { blur src 1 str 1 ssx 1 ssy 1 sf 1 sb 1 }  { sharpen src 1 str 1 ssx 1 ssy 1 sf 1 sb 1 }  { smear src 1 str 1 ssx 1 ssy 1 sf 1 sb 1 }} } toolbar_brush_hardness 0.200000003 toolbar_source_transform_scale {1 1} toolbar_source_transform_center {1024 576} colorOverlay {0 0 0 0} lifetime_type "all frames" lifetime_start 1858410 lifetime_end 1858410 view {} motionblur_on true motionblur_shutter_offset_type centred source_black_outside true name Roto1 selected true xpos 469 ypos 760}StickyNote { inputs 0 name StickyNote1 label "1) Press \"a\" to view the alpha of the rotoshape\n2) Note the motion blur samples\n3) Adjust the motion blur samples (This varies per Nuke Version) and note there is no change " selected true xpos 592 ypos 758}

2) With the viewer connected to the Roto node, view the output of the node via the Alpha channel

3) Using the timeline move forward a couple of frames and note the banding that is present.

4) Navigate to the motionblur knob (Shape tab in Nuke 7, Motion Blur tab in Nuke 11) and adjust it to a random value, eg. 5.

5) Continue to navigate frame by frame and see that the banding has not disappeared, despite the samples being adjusted.

Workaround

1) Create a Timeoffset node to reduce the frame number to something much lower, eg. Frame 1.

2) Resume your composting workflow

3) Prior to writing out/rendering your footage create another TimeOffset node and re-establish your original frame range, eg 1858415 - 1858500

Reproduced by support

This bug has been reproduced in:
Nuke 11.1v1 - CentOS 7.4 - Windows 7 - MacOS 10.13
Nuke 11.0v4 - CentOS 7.4
Nuke 10.5v7 - CentOS 7.4
Nuke 10.5v1 - CentOS 7.4
Nuke 10.0v6 - CentOS 7.4
Nuke 10.0v1 - CentOS 7.4
Nuke 9.0v9 - CentOS 7.4
Nuke 9.0v1 - CentOS 7.4
Nuke 8.0v7 - CentOS 7.4
Nuke 8.0v1 - CentOS 7.4
Nuke 7.0v10 - CentOS 7.4 - Windows 7 - MacOS 10.13

Earliest version tested
Nuke 7.0v10

Expected behaviour ​
There would be no banding when adjusting motionblur samples within the roto node at high frame ranges.

Actual behaviour ​
Banding occurs at high frame ranges when using motionblur within the roto node at high frame ranges.