aliasing with visible cell selection

When using the visible cell selection tool in ParaView on a fairly large mesh, the selection gets aliased if done from zoomed far out.

I actually noticed this in VTK with a custom application and figured I see if ParaView has the same issue which it does. Does anyone know of a way to work around this using the vtkOpenGLHardwareSelector?

Here’s a demo where I select from far out, observe the aliased selection, then make a selection while zoomed in which is not aliased:

This is indeed inherent to the implementation/design. It selects visible cells. If a cell has no contribution to screen pixels – which happens when you’re zoomed out – it is indeed not selected.

A work around it to use the select cells through, which compute a frustum and select all cells in this frustum.

Ah I see, thanks @utkarsh.ayachit!

@mwestphal - I wonder if there is a way that we could leverage the frustum and come up with some sort of way to only select cells that are traceable back to the camera… this might be a question better suited for the VTK discourse, but I’m curious if you think there might be a straightforward way to do this. Perhaps some sort of tracing within the frustum from the end of the frustum closest to the camera to the mesh in the scene?..

Why? I’ve been working with high resolution meshes lately where I need to make selections over a large area but the keep running into this aliasing issue. Perhaps as simple solution would be to bump up the screen resolution?

That seems doable, but not straightforward.

In your specific case, you could extract the surface and clip in the middle, before using select cells through.

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