Operators

# convert_point_3d_spher_to_cart (Operator)

## Name

convert_point_3d_spher_to_cart — Convert spherical coordinates of a 3D point to Cartesian coordinates.

## Signature

convert_point_3d_spher_to_cart( : : Longitude, Latitude, Radius, EquatPlaneNormal, ZeroMeridian : X, Y, Z)

## Description

The operator convert_point_3d_spher_to_cart converts the spherical coordinates of a 3D point, which are given in Longitude, Latitude, and Radius, into the Cartesian coordinates X, Y, and Z. The spherical coordinates Longitude and Latitude must be specified in radians. Furthermore, the Latitude must be within the range [-PI/2,+PI/2], where the latitude of the north pole is PI/2, and hence, the latitude of the south pole is -PI/2.

The orientation of the spherical coordinate system with respect to the Cartesian coordinate system can be specified with the parameters EquatPlaneNormal and ZeroMeridian.

EquatPlaneNormal determines the normal of the equatorial plane (longitude == 0) pointing to the north pole (positive latitude) and may take the following values:

'x':

The equatorial plane is the yz plane. The positive x axis points to the north pole.

'-x':

The equatorial plane is the yz plane. The positive x axis points to the south pole.

'y':

The equatorial plane is the xz plane. The positive y axis points to the north pole.

'-y':

The equatorial plane is the xz plane. The positive y axis points to the south pole.

'z':

The equatorial plane is the xy plane. The positive z axis points to the north pole.

'-z':

The equatorial plane is the xy plane. The positive z axis points to the south pole.

The position of the zero meridian can be specified with the parameter ZeroMeridian. For this, the coordinate axis (lying in the equatorial plane) that points to the zero meridian must be passed. The following values for ZeroMeridian are valid:

'x':

The positive x axis points in the direction of the zero meridian.

'-x':

The negative x axis points in the direction of the zero meridian.

'y':

The positive y axis points in the direction of the zero meridian.

'-y':

The negative y axis points in the direction of the zero meridian.

'z':

The positive z axis points in the direction of the zero meridian.

'-z':

The negative z axis points in the direction of the zero meridian.

Only reasonable combinations of EquatPlaneNormal and ZeroMeridian are permitted, i.e., the normal of the equatorial plane must not be parallel to the direction of the zero meridian. For example, the combination EquatPlaneNormal='y' and ZeroMeridian='-y' is not permitted.

Note that in order to guarantee a consistent conversion back from Cartesian to spherical coordinates by using convert_point_3d_cart_to_spher, the same values must be passed for EquatPlaneNormal and ZeroMeridian as were passed to convert_point_3d_spher_to_cart.

The operator convert_point_3d_spher_to_cart can be used, for example, to convert a camera position that is given in spherical coordinates into Cartesian coordinates. The result can then be utilized to create a complete camera pose by passing the Cartesian coordinates to create_cam_pose_look_at_point.

## Parallelization

• Multithreading type: reentrant (runs in parallel with non-exclusive operators).
• Processed without parallelization.

## Parameters

Longitude of the 3D point.

Latitude of the 3D point.

Restriction: ((- pi / 2) <= Latitude) && (Latitude <= (pi / 2))

EquatPlaneNormal (input_control)  string (string)

Normal vector of the equatorial plane (points to the north pole).

Default value: '-y'

List of values: 'x', 'y', 'z', '-x', '-y', '-z'

ZeroMeridian (input_control)  string (string)

Coordinate axis in the equatorial plane that points to the zero meridian.

Default value: '-z'

List of values: 'x', 'y', 'z', '-x', '-y', '-z'

X (output_control)  real(-array) (real)

X coordinate of the 3D point.

Y (output_control)  real(-array) (real)

Y coordinate of the 3D point.

Z (output_control)  real(-array) (real)

Z coordinate of the 3D point.

## Result

If the parameters are valid, the operator convert_point_3d_spher_to_cart returns the value 2 (H_MSG_TRUE). If necessary an exception is raised.