xform difference from maya

[Jonathan Garrett]

hi

I'm seeing a difference in xform for objects in maya vs an exported alembic scene

simplified scene contains just two objects - renderGeo_208 and renderGeo_766

there's a couple of levels of grouping, but all objects have an offset of 0 from their parent

  

  ABC

   |--GRP_glass

   |    `--Geometry

   |        `--anim_on_geo

   |            |--renderGeo_208

   |            |    `--renderGeo_Shape208

   |            `--renderGeo_766

   |                `--renderGeo_Shape766

   |--front

   |    `--frontShape

   |--persp

   |    `--perspShape

   |--persp1

   |    `--perspShape2

   |--side

   |    `--sideShape

   `--top

       `--topShape

maya timeine is frames 237 -> 333 (97 frames)

export cmdline:

  AbcExport -verbose -j "-frameRange 237 333 -uvWrite -file x:/tmp/test.abc";

here's the h5dump for object 208 on sample 89 (the last frame on which the object moves):

   ATTRIBUTE "0089" {

      DATATYPE  H5T_IEEE_F64LE

      DATASPACE  SIMPLE { ( 18 ) / ( 18 ) }

      DATA {

      (0): -1375.97, -166.102, 5.92368, -0.650441,

      (4): -0.694336, 21.9868, 90.0118, 0.0137763,

      (8): 123.641, 0.650441, 0.694336, -21.9868,

      (12): -0.650441, -0.694336, 21.9868, 0.650441,

      (16): 0.694336, -21.9868

      }

   }

there's 8 ops here:

  op0 kTranslate

    [0] -1375.9688590344488

    [1] -166.10157023745637

    [2] 5.9236813602364187 

  

  op1 kTranslate

    [0] -0.65044063497043680 

    [1] -0.69433593750000000 

    [2] 21.986816406250000 

  

  op2 kRotateZ

    [0] 90.011789000000007 

  

  op3 kRotateY

    [0] 0.013776324999999650 

  

  op4 kRotateX

    [0] 123.64102000000001 

  

  op5 kTranslate

    [0] 0.65044063497043680

    [1] 0.69433593750000000

    [2] -21.986816406250000

  

  op6 kTranslate

    [0] -0.65044063497043680 

    [1] -0.69433593750000000 

    [2] 21.986816406250000 

  

  op7 kTranslate

    [0] 0.65044063497043680

    [1] 0.69433593750000000

    [2] -21.986816406250000

the translation from the first one matches the offset in maya - and the rotate ops match what's going on in maya

presumably they're pre-multiplied in as they're applied, so we're translating to object center, rotating, then translating back before translating out into the world

but there looks to be too many local space translates and the net result of them all being applied causes the object to not line up with where maya says it ends up

maya: -13.76, -1.6661, 0.059

first op:

  op0 kTranslate

    [0] -1375.9688590344488 = -13.75968

    [1] -166.10157023745637 = -1.1661

    [2] 5.9236813602364187  = 0.059

our dump (ie. all the ops applied)

  :  frame  96 : pos -13.945 -1.6614 0.04066

which is close, but not correct

does anyone have any thoughts on what's causing the difference ?

(test files: http://goo.gl/EPx3U - saved from maya 2014, but I got the same issue in 2013.5)

thanks

Jonny

[Lucas Miller]

http://download.autodesk.com/us/maya/2009help/API/class_m_fn_transform.html

Is it possible that the Scalar Pivot Point is introducing numerical imprecision?

Does anyone know if this is actually skipped by Maya if there is no shear or scale? (even though the values are there?)

Lucas

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