[pdal] Scheming

[Howard Butler]

On Jul 2, 2011, at 7:39 AM, Howard Butler wrote:

> The Schema's dimension management needs to be addressed now. Consider:
> 
> - Scaling filter goes ints -> doubles.  This currently adds XYZ dims as doubles and attempts to remove XYZ int dimensions by marking the m_indexTable
> - Reprojection filter happens
> - descaling filter goes doubles -> ints.  This adds XYZ dims back as ints.  Again the deletion doesn't quite work though.  
> 
> The net effect of this is our schema ends up with three sets of XYZ dims in the m_dimensions vector, but only one Field_X is valid in the m_indexTable.
> 
> Ideas? Do we need m_indexTable at all?


Moving this to the list...

Some other questions:

- It seems SchemaLayout exists only to calculate the cumulative size of all of the DimensionLayouts, but the order of the DimensionLayouts (to be added to the SchemaLayout) is implicitly determined by the dimension order as they are added to the pdal::Schema's vector.  Can you clarify the intent of separating Schema/SchemaLayout and Dimension/DimensionLayout?  I'm a bit confused as to the advantages of keeping these separate as opposed to information that is updated on-the-fly as Dimensions are created or added to a Schema object.

- Do we want to bake in XML serialization of schema/dimension into those classes or keep them separate as we have them now?

Howard