rHEALPix

Classification

Miscellaneous

Available forms

Forward and inverse, spherical and ellipsoidal

Defined area

Global

Alias

rhealpix

Domain

2D

Input type

Geodetic coordinates

Output type

Projected coordinates

rHEALPix

rHEALPix is a projection based on the HEALPix projection. The implementation of rHEALPix uses the HEALPix projection. The rHEALPix combines the peaks of the HEALPix into a square. The square’s position can be translated and rotated across the x-axis which is a novel approach for the rHEALPix projection. The initial intention of using rHEALPix in the Spatial Computation Engine Science Collaboration Environment (SCENZGrid).

Usage

To run a rHEALPix projection on a WGS84 ellipsoidal model, use the following command:

proj +proj=rhealpix -f '%.2f' +ellps=WGS84 +south_square=0 +north_square=2  -E << EOF
> 55 12
> EOF
55 12   6115727.86  1553840.13

Parameters

Note

All parameters for the projection are optional.

+north_square

Position of the north polar square. Valid inputs are 0–3.

Defaults to 0.0.

+south_square

Position of the south polar square. Valid inputs are 0–3.

Defaults to 0.0.

+lon_0=<value>

Longitude of projection center.

Defaults to 0.0.

Note

The default convention is to interpret this value as decimal degrees. To specify radians instead, follow the value with the “r” character.

Example: +lon_0=1.5708r

See Projection Units for more information.

+ellps=<value>

The name of a built-in ellipsoid definition.

See Ellipsoids for more information, or execute proj -le for a list of built-in ellipsoid names.

Defaults to “GRS80”.

+x_0=<value>

False easting.

Defaults to 0.0.

+y_0=<value>

False northing.

Defaults to 0.0.

Further reading

  1. NASA

  2. Wikipedia