idea Documentation about true curves (aka CAD data) being stored separately from ST_GEOMETRY info (within SHAPE object/column) in Data Management Ideas

Documentation about true curves (aka CAD data) being stored separately from ST_GEOMETRY info (within SHAPE object/column)

Bud — Thu, 23 Mar 2023 20:43:40 GMT

Regarding SDE.ST_GEOMETRY shape object columns (Oracle):

Rumor has it, true curve info (aka CAD blob data) is stored separately from ST_GEOMETRY info — all within the same shape object/column. In other words, if we query the geometry via ST_GEOMETRY functions, we don't have access to true curve data, since it's stored in a separate object attribute (an LOB attribute).

(I imagine the wording above is wrong, but that's because I don't have any documentation to reference.)

Could information about the above be added to the docs? Otherwise, I'm just fumbling around in the dark.

I know the usual suspects are likely to say, "You can't access the CAD blob via ST_GEOMETRY anyway, so it's a moot point." That might be, but I still need to understand how it's been set up...so I can understand what the limitations are and how to work around them. For example, I need to understand how ST_GEOMETRY pre-densifies the true curves into straight segments. What logic is used for the pre-densification?

Documentation about ST_Geometry curves/CAD BLOB

Bud — Thu, 23 Mar 2023 20:44:23 GMT

(merged from a separate idea)

It would be helpful if documentation could be added about about curves and CAD BLOBs in ST_Geometry.

For example, expand on details like this:

From @ShannonShields
Features with curve geometry/circular arcs have two representations in enterprise geodatabases. The ST_Geometry shape stores a densified arc version of the geometry, and the true curve is stored in a blob format read by ArcGIS, but not by the DBMS.
https://community.esri.com/t5/geodatabase-questions/why-did-a-polygon-lose-76-sqft-shape-area-when/m-p/1269082/highlight/true#M8349

Some related GIS Stack Exchange posts:
https://gis.stackexchange.com/search?q=%5Bst-geometry%5D+cad

Re: Documentation about ST_Geometry curves/CAD BLOB

DanPatterson — Tue, 21 Mar 2023 13:20:47 GMT

Need documentation about true curves (aka CAD data... - Esri Community

Re: Documentation about true curves (aka CAD data) being stored separately from ST_GEOMETRY info (within SHAPE object/column)

SSWoodward — Thu, 23 Mar 2023 19:46:10 GMT

@Bud I have merged your two posts so that both of your comments are preserved in the same space.

Thanks as always for your ideas!