[WIP - DONT MERGE] fix(fov): fov was not working correctly for other planes

[IbrahimCSAE]

Context

The old code was not determining correctly which extent dimensions to use based on the view plane normal, now its fixed to use:

• Sagittal (looking along X): uses Y extent for width, Z extent for height
• Coronal (looking along Y): uses X extent for width, Z extent for height
• Axial (looking along Z): uses X extent for width, Y extent for height

[sedghi]

Looks reasonable

[tblock79]

This fix seems to break the stack viewports in many cases, and I am not sure if it would work for volumes with oblique orientation.

Using the legacy FOV calculation method for volume viewports could possibly be a quick fix:

if (imageData && !useLegacyMethod && (this.type !== ViewportType.ORTHOGRAPHIC)) {
    const extent = imageData.getExtent();
    const spacing = imageData.getSpacing();
    widthWorld = (extent[1] - extent[0]) * spacing[0];
    heightWorld = (extent[3] - extent[2]) * spacing[1];
}
else {
    ({ widthWorld, heightWorld } = this._getWorldDistanceViewUpAndViewRight(bounds, viewUp, viewPlaneNormal));
}

[IbrahimCSAE]

This fix seems to break the stack viewports in many cases, and I am not sure if it would work for volumes with oblique orientation.

Using the legacy FOV calculation method for volume viewports could possibly be a quick fix:

if (imageData && !useLegacyMethod && (this.type !== ViewportType.ORTHOGRAPHIC)) {

    const extent = imageData.getExtent();

    const spacing = imageData.getSpacing();

    widthWorld = (extent[1] - extent[0]) * spacing[0];

    heightWorld = (extent[3] - extent[2]) * spacing[1];

}

else {

    ({ widthWorld, heightWorld } = this._getWorldDistanceViewUpAndViewRight(bounds, viewUp, viewPlaneNormal));

}

Yeah this is broken thats why we changed the title to WIP. We could do legacy for Volume viewport but I believe it still doesn't always make the image take the full canvas. I'm leaving it up until we figure out something consistent

[tblock79]

That's definitely true. Using the legacy scaling as fallback might still make sense for the interim time because the current release version is often cropping a significant number of slices in volume viewports (thus, the legacy scaling should be preferable - even if not perfect).

[sedghi]

can you send us some screenshots of how much is it missing?

[tblock79]

Sure, here is an example (left is the current release, right is when using the legacy method as fallback for volume viewports). As you can see, a significant number of slices is outside the FOV after a camera reset. The impact might be dataset-dependent but I noticed it quite often.

[sedghi]

I think this is related issue #2168