# Tilted perspective¶

 Classification Azimuthal Available forms Forward and inverse, spherical projection Defined area Global Alias tpers Domain 2D Input type Geodetic coordinates Output type Projected coordinates

Tilted Perspective is similar to Near-sided perspective (`nsper`) in that it simulates a perspective view from a height. Where `nsper` projects onto a plane tangent to the surface, Tilted Perspective orients the plane towards the direction of the view. Thus, extra parameters specifying azimuth and tilt are required beyond nsper`'s `h`. As with `nsper`, `lat_0` & `lon_0` are also required for satellite position.

## Parameters¶

### Required¶

+h=<value>

Height of the view point above the Earth and must be in the same units as the radius of the sphere or semimajor axis of the ellipsoid.

### Optional¶

+azi=<value>

Bearing in degrees away from north.

Defaults to 0.0.

+tilt=<value>

Angle in degrees away from nadir.

Defaults to 0.0.

+lon_0=<value>

Central meridian/longitude of natural origin, longitude of origin or longitude of false origin (naming and meaning depend on the projection method).

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=1.570796r

+lat_0=<value>

Latitude of natural origin, latitude of false origin or latitude of projection centre (naming and meaning depend on the projection method).

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: +lat_0=1.570796r

+R=<value>

Radius of the sphere, given in meters. If used in conjunction with `+ellps`, `+R` takes precedence.