Is it possible to do global transformations of Grids with nanovdb?

[stevenewbold]

I can see with openvdb that we can use a matrix to transform a grid, but I can't see a similar way of doing this with nanovdb. Is this possible?

I'm trying to write something light-weight (hence nanovdb) for rendering volumes, but I need to be able to allow simple affine transformations of the whole grid to a different WorldSpace. While I guess I can incorporate this myself as part of the rendering process, being able to scale/rotate/move a grid would make things a lot simpler.

Apologies if I'm simply missing something... pretty new to both openvdb and nanovdb.

[alessandroAM]

If I understood your question correctly, you can simply transform a grid (translate/rotate/scale) like in this example:

openvdb::math::Mat4d mat = openvdb::math::Mat4d::identity(); openvdb::math::Transform::Ptr linearTransform = openvdb::math::Transform::createLinearTransform(mat); linearTransform->postTranslate(openvdb::Vec3d(100, 0, 0) ); vdbGrid->setTransform(linearTransform);
Here I translate the grid 100 units on the X axis.

[iaomw]

This is exactly what I want to do, but exclusively with nanovdb and not openvdb. I'm looking at nanovdb:map() to see if this can be used in a similar way by defining the world and inverse world matrix.

Hi, any update on how to transform nanovdb grid?

[apradhana]

nanovdb::Map is defined here. In my application I use it to go from coord space to world space by applying applyMapF. Other examples can be found here.

[dchristopherfennell]

I'm trying to orient my nanovdb volume. Reading the above, it appears that openvdb has an easy way to do this by adding a transform.

How is this done using nanovdb? I'm looking at nanovdb::Map, but it's not straight forward on how to rotate orient the volume.

[stevenewbold]

In the end I transformed my rays into the grid space to get the appearance of transforming the grid in world space. Would be much easier to have an easy way to apply a transformation to the grid itself.

[dchristopherfennell]

It doesn't make sense to me that there isn't an easy way to orient the volume like in openvdb. Transforming rays into grid space seems overly complicated, but as a last resort, I may have to do that.