16.65. sfs_blendΒΆ

The sfs_blend tool is a very specialized DEM blending program developed for use in conjunction with Shape-from-Shading (Section 16.64). It replaces in an SfS-produced DEM height values that are in permanent shadow with values from the initial guess DEM used for SfS (which is typically the LOLA gridded DEM), with a transition region between the two DEMs.

Motivation and an example of an invocation of this tool are given in the SfS usage chapter.

Command-line options:

--sfs-dem <arg>

The SfS DEM to process.

--lola-dem <arg>

The LOLA DEM to use to fill in the regions in permanent shadow.

--max-lit-image-mosaic <arg>

The maximally lit image mosaic to use to determine the permanently shadowed regions.

--image-threshold <float>

The value separating permanently shadowed pixels from lit pixels in the maximally lit image mosaic.

--lit-blend-length <float>

The length, in pixels, over which to blend the SfS and LOLA DEMs at the boundary of the permanently shadowed region towards the lit region. Because of the weight blur below, the effective blending length can be somewhat bigger than this.

--shadow-blend-length <float>

The length, in pixels, over which to blend the SfS and LOLA DEMs at the boundary of the permanently shadowed region towards the shadowed region. Because of the weight blur below, the effective blending length can be somewhat bigger than this.

--weight-blur-sigma <float (default 0)>

The standard deviation of the Gaussian used to blur the weight that performs the transition from the SfS to the LOLA DEM. A higher value results in a smoother transition (this does not smooth the DEMs). The extent of the blur is about 7 times this deviation though it tapers fast to 0 before that. Set to 0 to not use this operation.

--min-blend-size <int (default 0)>

Do not apply blending in shadowed areas of dimensions less than this, hence keeping there the SfS DEM.

--output-dem <arg>

The blended output DEM to save.

--output-weight <arg>

The weight showing the proportion of the SfS DEM in the blend with the LOLA DEM (1 is for purely SfS and 0 is for purely LOLA).

--threads <integer (default: 0)>

Select the number of threads to use for each process. If 0, use the value in ~/.vwrc.

--cache-size-mb <integer (default = 1024)>

Set the system cache size, in MB.

--tile-size <integer (default: 256 256)>

Image tile size used for multi-threaded processing.

--no-bigtiff

Tell GDAL to not create bigtiffs.

--tif-compress <None|LZW|Deflate|Packbits (default: LZW)>

TIFF compression method.

-v, --version

Display the version of software.

-h, --help

Display this help message.