BACKGROUND_STRATEGY_ZERO and BACKGROUND_STRATEGY_ID seem like bad ideas

[Caleb Rottman]

Is there any good reason to keep ZERO and ID background strategies (also VAL, which i don't think has any functionality at this point)? If these are used, then the outside (but only higher coordinate) edges of Image3Ds/Field3Ds are considered to be background. Even worse, if you are using a 2D images/fields, then the whole image is considered background.

For example, this is relevant with something like ApplyH(Field3D a_o, Field3D a_i, Field3D h, BackgroundStrategy bg) which has no default background strategy.

If we want ZERO or ID background conditions, i think we would always want to use PARTIAL_ZERO or PARTIAL_ID, so it might be a good idea to just get rid of ZERO and ID boundary conditions.

[Caleb Rottman]

I see that BACKGROUND_STRATEGY_VAL is in development, but it might be a good idea to do BACKGROUND_STRATEGY_PARTIAL_VAL instead.

[Sam Preston]

Yes, like the APPROX finite difference boundary condition, VAL and ZERO are just legacy background strategies -- PARTIAL_VAL and PARTIAL_ZERO should always be preferred. I agree there's no need to keep them around any longer, so I'm marking their removal for the next release.

[Caleb Rottman]

Issue #49 was marked as a duplicate of this issue.