[Insight-users] A question about Spatial Objects Transformations: ObjectToNode Transform and ObjectToParent Transform

[Dawood Masslawi]

Dear Haiyong,
ObjectToNode transform is a type of ObjectToParent transform. The 
coordinate system of both Nodes and Parent objects is in physical
space the difference is in their object type and properties that's
why there is no NodeToParent transform. 
You can not think of the two coordinate systems as one since 
one is in internal data coordinate system and the other is in 
physical coordinate system.
The ObjectToParent transform is a ObjectToParentObject transform.
Best regards,
Dawood Almasslawi

>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>><<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>><<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<

Hello,

I have read the section in the ITK software guide PDF about Spatial
Objects, there are two transformations that are not clear to me:
ObjectToNode Transform and ObjectToParent Transform.

Please refer to the Figure 5.1 in ITK software guild PDF. In this
figure, it seems that an object (spatial object) has a coordinate
system, and Node has a coordinate system too. What's the difference
between them? After reading the source code in
itk::AffineGeometryFrame, it looks like that the ObjectToNode
transform will always be identity. Can I regard those two coordinate
systems as one?

Also, the name ObjectToParent transform is ambiguous. Is this a
ObjectToParentNode or ObjectToParentObject?

BTW, please correct the following paragraph in the ITK software guide
PDF (page 106), there are errors:

"... As one can see from the figure 5.1, the ObjectToParentTransform
is composed of two transforms: ObjectToNodeTransform and
NodeToParentNodeTransform.
The ObjectToNodeTransform is not applied to the children, but the
ObjectToNodeTransformis.
Therefore, if one sets the ObjectToParentTransform, the ObjectToNodeTransform
is modified."

Thanks.

Haiyong


      
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.itk.org/pipermail/insight-users/attachments/20110111/ffcc8a2c/attachment.htm>