Simulates the ArcSDE 9.1 conversion on a feature by performing ArcSDE translation, scaling, and coordinate snapping. Useful in verifying what the data will look like once it is in an ArcSDE.

 

When writing to SDE 9.1, things are not always so simple. Coordinates in low precision are stored in database as 31 bit positive integers. Features will be rejected where their coordinates have a greater precision than is allowed for in the database. When snapping features to the SDE grid, self-intersections can be introduced by ArcSDE itself!

 

The ArcSDEGridSnapper requires the following information: a false origin for x,y,z coordinate values and a scale factor. The ArcSDEGridSnapper simulates coordinate transformation and records duplicates. It will snap all feature coordinates to match the precision specified, thus making the feature compatible with your ArcSDE database. It's a much preferable alternative to the CoordinateRounder.

 

By quickly simulalating data conversion to ArcSDE 9.1, the ArcSDEGridSnapper allows for the analysis of data accuracy. The problematic data output from the ArcSDEGridSnapper can be further processed in the workspace (removal of dangles/sliver polygons for example) before the data is loaded into SDE.

 

Please see the link to see what ESRI considers valid geometry in ArcSDE: ESRI's 9.1 Page on Shape Validation, ESRI's 9.3 Shape Verification Rules and Esri ArcMap 10.0 Geometry validation on tables containing ST_Geometry columns

There is currently no support in the ArcSDEGridSnapper for the high precision coordinates available in ArcGIS 9.3 or higher.

It is sometimes difficult to know how to set the values of the ArcSDEGridSnapper and how these map to the values defined in ArcCatalog and the FME Geodatabase or ArcSDE writer.

Here is a general guideline

In ArcGIS, select a feature class. Right click -> Properties.

ArcCatalog <--> ArcSDEGridSnapper <--> Geodatabase (ArcSDE) writer <--> ArcSDE writer

Domain Tab (Min X) <--> Minimum X <--> X Origin <--> X Origin

Domain Tab (Min Y) <--> Minimum Y <--> Y Origin <--> Y Origin

Resolution Tab (XY Resolution) <--> Scale <--> Scaling Factor <--> X,Y Scale

Domain Tab (Min Z) <--> Minimum Z (if 3D) <--> Z Origin <--> Z Origin

Resolution Tab (Z Resolution) <--> Z Scale (if 3D) <--> Z Scaling Factor <--> Z Scale