Migrating Predefined Coordinate Reference Systems
Some coordinate reference systems were predefined in Carmenta Engine 4.x, but have been renamed or are no longer predefined. If they were used in a .p file, they will be migrated automatically to a .px file. Otherwise, you have to migrate your application code.
These coordinate reference systems (known as RefSystems in 4.x) can be divided into four groups:
RefSystems available under new names
Some predefined 4.x RefSystems have a predefined equivalent in version 5.x.
Predefined RefSystem in 4.x | Exactly equivalent predefined Crs in 5.x |
|---|---|
defaultRectangular | |
rectangular | |
screenRefSys | |
WGS84mercator1SP_ellipsoid | |
WGS84mercator1SP_web |
RefSystems lacking a predefined equivalent, but available via EPSG code
Some predefined 4.x RefSystems have no predefined equivalent in version 5.x, but are easy to construct from EPSG code.
Predefined Swedish RefSystem in 4.x | Exactly equivalent authority code in 5.x |
|---|---|
RT90lola | 4124 |
RT90_7_5gonW | 3845 |
RT90_2_5gonW | 3847 |
SWEREF99_2_5gonW | 3847 |
SWEREF99 | 3006 |
SWEREF99TM | 3006 |
The equivalent coordinate reference system can easily be created in code with the Crs.FromAuthorityAndCode method using epsg as authority and the codes listed above,
If they were used in a .p file, the automatic migration will create a replacement in this way.
 |
RefSystems having an approximate predefined equivalent
Three of the predefined Mercator RefSystems in 4.x can be migrated either approximately or exactly.
Predefined RefSystem in 4.x | Approximately equivalent predefined Crs in 5.x | Exactly equivalent Crs in 5.x |
|---|---|---|
WGS84mercator1SP | Crs.Wgs84MercatorWeb | Use GeodeticDatum.Wgs84 and a MercatorProjection with sphereRadiusSource = RadiusFromArgument and sphereRadius = 6366707.0194937075 |
WGS84mercatorDegrees | Crs.Wgs84MercatorWeb | As above, but use a lengthUnit that equals 111120 meters. |
mercatorMeter | Crs.Wgs84MercatorWeb | As above, but use scaleFactor = 0.8 and LengthUnit.Meter as lengthUnit. |
If they were used in a .p file, the automatic migration to .px will be careful to create their exact equivalent, using the new names WGS84mercator1SP_LEGACY, WGS84mercatorDegrees_DEPRECATED, and mercatorMeter_LEGACY. This is because the exact equivalence is necessary if your application had data stored in these RefSystems.
However, if you know that you used these Mercator RefSystems only for presentation (in a View), not for data storage, it is better to replace them by the new predefined Crs.Wgs84MercatorWeb, which is similar. However, any coordinates that are hard-coded in your application (for example, the view center at startup) must be migrated by a multiplication with a constant factor.
Predefined RefSystem in 4.x | Migration factor |
|---|---|
WGS84mercator1SP | 1.00179527352 |
WGS84mercatorDegrees | 111319.49079 |
mercatorMeter | 1.252244092 |
RefSystems having no predefined equivalent, and no EPSG code
The predefined WGS84miller1SP of 4.x has no predefined replacement. It can be approximated by a Crs based on GeodeticDatum.Wgs84 and a MillerCylindricalProjection with default properties. This is good enough if you used the WGS84miller1SP only for presentation. If you had data stored in WGS84miller1SP, you have to construct an exact equivalent, which is possible as a Crs based on GeodeticDatum.Wgs84 and a MillerCylindricalProjection with a lengthUnit that equals 1.00179527352 meters.