INSADJUSTDEM

Description

INSADJUSTDEM corrects the random offset and tilt of relative DEMs generated by INSUNWRAP based upon the coarse reference DEM specified by the user. The correction for random offset and tilt is necessary to convert the relative DEM to absolute values. The correction to absolute values is required before a DEM can be geocoded by modules such as GEOCODEDEM.

Parameters

insadjustdem(filref, dbic_ref, fili, dbic_dep, filo)

Name	Type	Caption	Length	Value range
FILREF *	str	The filename of the reference DEM.	1 -
DBIC_REF	List[int]	The channel containing the digital elevations.	0 - 1
FILI *	str	The filename of the relative DEM.	1 -
DBIC_DEP	List[int]	The channel containing the elevations to be corrected.	0 - 1
FILO *	str	The name of the output file.	1 -

* Required parameter

Parameter descriptions

FILREF

The filename of the coarse reference DEM to use for the correction.

DBIC_REF

Specifies the channel containing the elevation values. If the ELEVATION_DATUM metadata tag is not provided, mean sea level (MSL) is assumed.

The default value is 1

FILI

The filename of the relative DEM to be corrected for offset and tilt.

DBIC_DEP

Specifies the channel of the relative DEM to be corrected. The default value is 11.

FILO

This parameter specifies the name of the file to be generated containing the elevation values corrected for offset and tilt. This file must not already exist.

Details

The reference DEM FILREF is reprojected into the co-ordinate system of the relative DEM FILI. The reference DEM is not required to have the same sample size or projection as the relative DEM. The datum of the reference DEM is assumed to be mean sea level (MSL) unless indicated otherwise and the elevation units are assumed to be meters. The reprojected values are subtracted from the relative DEM to generate a difference image. A second order surface of best fit is generated from this difference image and is subtracted from the relative DEM to generate the corrected image. The geocoded output DEM FILO contains a single layer of floating point elevation values in meters relative to the WGS84 ellipsoid.

Example

Use a coarse DEM to remove the offset and tilt in the relative DEM generated from an unwrapped interferogram and written to channel 2.

from pci.insadjustdem import insadjustdem

filref   = "Reprojected_DEM.pix"
dbic_ref = [1]
fili     =  "Unwrapped_Interferogram.pix"
dbic_dep = [2]
filo     = "Corrected_DEM.pix"

insadjustdem(filref, dbic_ref, fili, dbic_dep, filo)