Adding a Web Mercator projection coordinate system to Oracle spatial

Resources:

1. The most important reference article, basically is to do this!!! : Https://www.inf.unibz.it/dis/wiki/doku.php?id=students:minnerebner:oracle:addingsrid.

2. Example reference: http://www.cnblogs.com/cleverxy/archive/2012/04/28/2474563.html

Step 1 is starting from 0, this should have some basis, you can look at the inside of the 8801~8807, 9802~9807 explanation, and then go to the database to check these tables.

3. Two other forums/blogs that look more informative:

Oracle Error Query: Http://www.serkey.com/oracle-incorrect-result-from-sdo-filter-bct53x.html#beuerd

Combine spatial with it: http://spatialdbadvisor.com/

Web Mercator Projection

In the help of ArcGIS http://resources.arcgis.com/zh-cn/help/main/10.1/index.html#//003r00000038000000 the first paragraph reads: "There are two types of simulations The method used by the Mercator projection for WEB services. If the Mercator implementation supports an ellipsoid (ellipse body), the projected coordinate system must be based on a sphere-based geographic coordinate system. This requires that the sphere equation be used. The implementation of the Mercator auxiliary sphere only has a sphere equation. In addition, if the geographic coordinate system is ellipsoid-based, it also has a projection parameter that identifies what the sphere radius is used for. When the default value is 0 (0), the long half axis is used. "At first glance a little confusing, and think of an article before read: http://hmfly.info/2012/10/17/mercator%E9%82%A3%E4%BA%9B%E4%BA%8B%E5%84%BF/, where the Web The differences between Mercator and web Mercator (auxiliary Sphere) are compared between 3785 and 3857. My understanding, corresponding to the ArcGIS help that paragraph, should be method one is 3785, method two corresponds to 3857, "it also has a projection parameter" refers to "auxiliary_sphere_type:0.0" bar. There is no confusion behind it, just consider using 3857.

About coordinates and projections can also look at the help of ArcGIS, from the ellipsoid, geodetic datum, coordinate reference system, projected coordinate systems slowly gradually clear.

Additional instructions for defining the Web Mercator projected coordinate system (link 1):

1. Define ellipsoid: Add the required ellipsoid definition in the Mdsys.sdo_ellipsoids table, where inv_flattening (the inverse of the flattening rate) is set to a large number of 1.000E+12, which means that only the length of the long half axis is used.

2. Define geodetic Datum: Add the Geodetic datum definition in the Mdsys.sdo_datums table, where the ellipsoid parameter is defined in the 1th step;

3. Defining a geographic coordinate system: Add coordinate reference systems to the Mdsys.sdo_coord_ref_system table: where the coordinate system type Coord_ref_sys_kind and the coordinate system designator coord_sys_id are consistent with the definition in Sdo_coord_sys.

4. Define a projection transformation rule: Add a projection transformation definition to the mdsys.sdo_coord_ops and define the latitude of natural origin (Origin parallels), longitude of natural origin (in the coordinate reference frame of the 3rd step). Origin longitude), false_easting East Pseudo-offset, false_northing North pseudo-offset and other parameters.

5. Define a projected coordinate system: the target coordinate system type is a Cartesian coordinate system, which is based on the previously defined ellipsoid, geographic coordinate system, and projection transformation rules, resulting in a 3857 projected coordinate system.

6. Define a conversion of 8307 to 3857.

This involves a number of code names and attribute entries defined in Oracle spatial, which can be found in the official documentation:

http://docs.oracle.com/cd/B28359_01/appdev.111/b28400/sdo_cs_concepts.htm#SPATL640

Attach a little Chinese information:

　　 sdo_coord_ops the definition of a coordinate type in table:

One-dimensional coordinate system:

Vertical (VERTICAL): These coordinate systems have a typical application in modeling the Earth's surface height. This height can be either the geoid height or the ellipsoidal height (in the reference system, the height of the ellipsoid that approximates the Earth's surface).

Two-dimensional coordinate system:

Geographic two-dimensional (geographic2d): This type of coordinate system achieves the approximate longitude and latitude of the Earth's surface by referring to the ellipsoid. This type is also known as the geodetic coordinate system.

Projection (Projected): This type of coordinate system defines how the longitude and latitude of a geographic two-dimensional reference system are projected onto a Cartesian coordinate. As discussed in the "Projected coordinate system" earlier, you can use different types of coordinate projection techniques, such as isometric and equidistant projections.

3D coordinate system:

Geographic three-dimensional (geographic3d): This type of coordinate system determines the longitude, latitude, and Ellipsoid Heights based on a geodetic datum (ellipsoid).

Geocentric (geocentric): This type of coordinate system is centered on the Earth's core to determine the X, Y, z values (not the surface ellipsoid in the geographic three dimensions).

Compounding (Compound): This method combines a geographic two-dimensional (latitude-longitude) or projected coordinate system with a vertical coordinate system that specifies height based on gravity, elevation, and so on.

Local coordinate system

Engineering: These coordinate systems are the coordinate systems of some specific applications. They are related to or unrelated to the data on the surface of the Earth, but the data is often treated as a Cartesian coordinate system.

Thank you all for referencing the work of the link author!

Adding a Web Mercator projection coordinate system to Oracle spatial