#168: Addition of grid mapping for radar and lidar data in radial coordinates
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Reporter: mikedixon | Owner: cf-conventions@…
Type: enhancement | Status: new
Priority: medium | Milestone:
Component: cf-conventions | Version:
Resolution: | Keywords: radar lidar grid mapping
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Description changed by mikedixon:
Old description:
> == Introduction ==
>
> Radars and Lidars sample the atmosphere using a pulse of energy
> transmitted from an instrument along a line of sight away from the
> instrument, with a specified beam width (solid angle). The received
> signal is sampled over time, which allows for the estimation of the
> distance of the target from the instrument.
>
> The raw data is stored in radial (polar) coordinates. The location in
> space, especially in the vertical, is dependent on the propagation of the
> energy through the atmosphere. Vertical gradients of the index of
> refraction lead to complexities in determining the height of the target.
>
> The organization and interpretation of radial data of this type is not
> supported by any of the standard grid mapping types currently supported
> by CF.
>
> Therefore, in order for the CfRadial radar and lidar format to be
> formally recognized by the CF user community, we are proposing the
> addition of a grid mapping specifically for radar and lidar data.
>
> == Proposed grid mapping name ==
>
> We propose the use of the name “radar_lidar_radial_scan”.
>
> == Grid mapping parameters ==
>
> The following example from a '''CfRadial''' file shows the proposed
> parameters:
>
> {{{
> grid_mapping:grid_mapping_name = "radar_lidar_radial_scan" ;
> grid_mapping:longitude_of_projection_origin = -104.545806884766 ;
> grid_mapping:latitude_of_projection_origin = 39.7866401672363 ;
> grid_mapping:height_of_projection_origin = 1709. ;
> }}}
>
> The latitude and longitude are in degrees.
>
> The height is in meters MSL.
>
> The height_of_projection_origin parameter is analogous to the
> perspective_point_height in the vertical perspective projection.
>
> The document is maintained at:
>
> https://github.com/NCAR/CfRadial/tree/master/docs
New description:
== Introduction ==
Radars and Lidars sample the atmosphere using a pulse of energy
transmitted from an instrument along a line of sight away from the
instrument, with a specified beam width (solid angle). The received signal
is sampled over time, which allows for the estimation of the distance of
the target from the instrument. The samples in range are frequently
referred to as 'gates'.
The raw data is stored in radial (polar) coordinates. The (x,y) location
of a gate may be determined using traditional great-circle techniques,
since these are line-of-sight instruments and the propagation is assumed
to be along a straight line in (x,y). In the vertical (z) dimension, a
standard model of atmospheric refractive index is generally assumed for
locating the height of the gate.
The organization and interpretation of radial data of this type is not
supported by any of the standard grid mapping types currently accepted by
CF.
Therefore, in order for the CfRadial radar and lidar format to be formally
recognized by the CF user community, we are proposing the addition of a
grid mapping specifically for radar and lidar data.
== Proposed grid mapping name ==
We propose the use of the name “radar_lidar_radial_scan”.
== Grid mapping parameters ==
The following example from a '''CfRadial''' file shows the proposed
parameters:
{{{
grid_mapping:grid_mapping_name = "radar_lidar_radial_scan" ;
grid_mapping:longitude_of_projection_origin = -104.545806884766 ;
grid_mapping:latitude_of_projection_origin = 39.7866401672363 ;
grid_mapping:height_of_projection_origin = 1709. ;
}}}
The latitude and longitude are in degrees.
The height is in meters MSL.
The height_of_projection_origin parameter is analogous to the
perspective_point_height in the vertical perspective projection.
The supporting documents are maintained at:
https://github.com/NCAR/CfRadial/tree/master/docs
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Ticket URL: <https://cf-trac.llnl.gov/trac/ticket/168#comment:9>
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