Home: The Essential FDO
Data Store Management API
The Essential FDO
Glossary
Spatial Context API
The
following table defines default values for the spatial context properties
for the providers (MySQL and SDF) that support the creation of a
data store and example sets of spatial context properties extracted
from ODBC, WFS, and WMS sources created by a non-FDO process.
Properties/Provider |
MySQL |
ODBC |
SDF |
WFS |
WMS |
Notes |
Coordinate system |
Cartesian |
Cartesian |
Cartesian |
EPSG:4326 |
EPSG:4326 |
1 |
Extent type |
Static |
Static |
Dynamic |
Static |
Static |
2 |
Extent |
Not NULL |
Not NULL |
NULL |
Not NULL |
Not NULL |
3 |
Unit dimension |
XY |
XY |
Undefined |
XY |
XY |
4 |
XY tolerance |
.001 |
.001 |
0 |
.01 |
.001 |
5 |
Z tolerance |
.001 |
.001 |
0 |
.01 |
.001 |
5 |
Active |
False |
F |
True |
F |
F |
6 |
Note
-
EPSG:4326 is a Layer Coordinate Reference
System (CRS) as defined in the OpenGIS Web Map Service (WMS) Implementation
Specification, OGC 04-024, version 1.3, dated August 2, 2004.
- A
static extent type means that the extent is defined at the time of
the creation of the spatial context using the FdoICreateSpatialContext command.
A dynamic extent type means that the extent may change as features
are added so that it always encloses all of the features.
- The
default extents expressed in AGF text format for the various providers
are as follows:
-
MySQL, : POLYGON ((-2000000 -2000000,
2000000 -2000000, 2000000 2000000, -2000000 2000000, -2000000 -2000000))
- The
dimensionality is that of the extent. It is not set directly.
- See
Tolerance.
-
ArcSDE and MySQL providers can have
multiple spatial contexts defined and can, therefore, show contexts in
the reader that are not active.