Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

ISIS Documentation

cnet2dem

Create a digital elevation model from one or more control network files.

The cnet2dem applicaton produces an interpolated digital elevation model (DEM) from one or more control networks. There are fourteen different algorithms that may be selected that provide either absolute radius values or other information, such as radius and point distance statistics, computed at each output DEM pixel value. The range and type of the DEM generated from cnet2dem is a standard ISIS map definition or a projected ISIS cube file containing a map definition. You can select any number of algorithms in the ALGORITHM parameter. The output cube will contain the same number of bands in the same order algorithms are specified in the parameter. The BandBin group Name parameter will also contain the name of the algorithm that cooresponds to the data contained in each band.

Note that the control network is expected to be the output results of the bundle adjustment computed by jigsaw. Additionally, jigsaw must have been used to solve for radius. Otherwise, you will be using the apriori radius which is typically the PCK defininition (will will result in the ellipsoid).

The adjusted latitude/longitude coordinate is used to compute the location of all the control points. The adjusted coordinates are compute by jigsaw. If it doesn't exist, the apriori coordinate will be used but know that this coordinate is typically computed from each reference image in each control point (so it may not be consistent).

Also, in some cases, one or more of the algorithm radius bands in the output of cnet2dem may be sufficient for direct use as an ISIS shape model (after demprep is run!). However, this is generally not the case and some of the radius bands may require a series of filters to smooth out the results.

Categories

History

Kris Becker2015-11-13 Original Version
Tyler Wilson2016-03-10 Minor documentation corrections.

Parameters

Input

A single control network file used to create the point cloud to produce the interpolated output DEM radius at each output pixel.
Type filename
File Mode input
Internal Default None
Filter *.net

A list of control network files that are combined into the point cloud to produce the interpolated output DEM radius at each output pixel.
Type filename
File Mode input
Internal Default None
Filter *.lis

A standard ISIS map definition file or a map projected ISIS cube file containing a mapping group. This file will be used to create the output DEM ISIS cube.
Type filename
File Mode input
Filter *.map *.cub

Output

Specifies the name of an output ISIS cube file that is created to write the DEM. The output DEM may require demprep to be run on it before it can be used as an ISIS DEM shape model.
Type cube
File Mode output
Pixel Type real
Filter *.cub

If this option is selected, pixels outside the latitude/longtiude range will be trimmed (set to null). This is useful for certain projections whose lines of latitude and longitude are not parallel to image lines and sample columns.
Type boolean
Default FALSE

Parameters

This parameter allows the user to specify the size of the radius search at each output map pixel. If not provided, the pixel resolution of the projection is used to specify the search diameter.
Type string
Default RADIAL
Option List:
Option Brief Description
RADIALSearch for points within a given DISTANCE. Specify the point cloud to be searched with a radial distance query. The point of origin is the center of each output map pixel geometric (i.e., latitude/longitude) coordinate. Use the DISTANCE parameter to specify the maximum search range.
NEIGHBORSFind NEIGHBORS closest points. Populate the map with the control points nearest the output DEM pixel center geometric (i.e., latitude/longitude) coordinate. Use the NEIGHBORS parameter to specify how many nearest points to use.
BOTHAppy both RADIAL and NEIGHBOR searches if needed. Use both the RADIAL and NEIGHBORS options to determine the result at the output DEM pixel center geometric (i.e., latitude/longitude) coordinate. The RADIAL option is applied first. If MINPOINTS are not found from this query, then the NEIGHBORS option is applied.

Radial distance in meters to search for control points measured from the center of the ouput map pixel.
Type double
Internal Default None

Number of leafs in the kd-tree structure.
Type integer
Default 10

Specify number of control points that will be selected in the nearest NEIGHBOR search query to produce the output DEM pixel values.
Type integer
Default 0

Specify number of minimum number of points to accept from the RADIAL search query of the point cloud at each output DEM pixel. If the result set for each pixel does not have at least MINPOINTS, NULL values will be written to the output DEM pixel.
Type integer
Default 0

If provided, a noise filter is applied to the radius of the point set at each output pixel. The SIGMARADIUS is the number of standard deviations from the median radius from all control points.
Type double
Internal Default None

This parameter provides numerous methods to compute the output radius value for a given latitude, longitude and map grid point. Any number of methods can be specified by enetering a comma-delimited lisf of the method names.

DEM Data Value Output Function Options
Name Parameters Description
AverageRadius None For all control points found in the RADIAL and/or NEARESTNEIGHBOR kd-tree search, computes the average radius value (the average Euclidean distance of all points from the surface to the center of the body).
MaximumRadius None Computes the maximum radius (in meters) of the control points.
MinimumRadius None Computes the minimum radius (in meters) of all control points.
MedianRadius None Computes the median radius (in meters) of all control points.
StandardDeviationRadius None Computes the standard deviation (in meters) of the radii of the control points.
MaximumDistance None Computes the maximum surface distance (in meters) of all control points with respect to the latitude, longitude coordinates of the central pixel.
MinimumDistance None Computes the minimum surface distance (in meters) of all control points with respect to the latitude, longitude coordinates of the central pixel.
MedianDistance None Computes the median surface distance (in meters) of all control points with respect to the latitude, longitude coordinates of the central pixel.
AverageDistance None Computes the average surface distance (in meters) of all control points with respect to the latitude, longitude coordinates of the central pixel.
StandardDeviationDistance None Computes the standard deviation (in meters) of the surface distance of all control points with respect to the latitude, longitude coordinates of the central pixel.
FrankeNelsonRadius None Computes the radius of the control points (in meters) using the Franke-Nelson method.
ShepardsRadius None Computes the radius of the control points (in meters) using Shepard's weighted algorithm.
NaturalNeighborRadius None Computes the radius of the control points (in meters) using the Nearest Neighbor interpolation algorithm.
TypeCount None Returns the total number of pixels in the point collection. It additionally applies a signed (+/-1) value to indicate if the FLANN (Fast Library for Approximate Nearest Neighbors) search type was nearest neighbor (-1) or radius (+1).
Type string