ComputePolylineFeatureFromImage¶

This application computes the chosen descriptors for each studied polyline contained in the input VectorData.

Description¶

The first step in the classifier fusion based validation is to compute the chosen descriptors for each studied polyline.

Parameters¶

Elevation management

Input Image -in image Mandatory
An image to compute the descriptors on.

Vector Data -vd vectorfile Mandatory
Vector data containing the polylines where the features will be computed.

Elevation management ¶

This group of parameters allows managing elevation values. Supported formats are SRTM, DTED or any geotiff. DownloadSRTMTiles application could be a useful tool to list/download tiles related to a product.

DEM directory -elev.dem directory
This parameter allows selecting a directory containing Digital Elevation Model files. Note that this directory should contain only DEM files. Unexpected behaviour might occurs if other images are found in this directory.

Geoid File -elev.geoid filename [dtype]
Use a geoid grid to get the height above the ellipsoid in case there is no DEM available, no coverage for some points or pixels with no_data in the DEM tiles. A version of the geoid can be found on the OTB website(https://gitlab.orfeo-toolbox.org/orfeotoolbox/otb-data/blob/master/Input/DEM/egm96.grd).

Default elevation -elev.default float Default value: 0
This parameter allows setting the default height above ellipsoid when there is no DEM available, no coverage for some points or pixels with no_data in the DEM tiles, and no geoid file has been set. This is also used by some application as an average elevation value.

Feature expression -expr string Mandatory
The feature formula (b1 < 0.3) where b1 is the standard name of input image first band

Feature name -field string Mandatory
The field name corresponding to the feature codename (NONDVI, ROADSA…)

Output Vector Data -out vectorfile Mandatory
The output vector data containing polylines with a new field

Load parameters from XML -inxml filename.xml
Load application parameters from an XML file.

Save parameters to XML -outxml filename.xml
Save application parameters to an XML file.

Examples¶

From the command-line:

otbcli_ComputePolylineFeatureFromImage -in NDVI.TIF -vd roads_ground_truth.shp -expr "(b1 > 0.4)" -field NONDVI -out PolylineFeatureFromImage_LI_NONDVI_gt.shp

From Python:

import otbApplication

app = otbApplication.Registry.CreateApplication("ComputePolylineFeatureFromImage")

app.SetParameterString("in", "NDVI.TIF")
app.SetParameterString("vd", "roads_ground_truth.shp")
app.SetParameterString("expr", "(b1 > 0.4)")
app.SetParameterString("field", "NONDVI")
app.SetParameterString("out", "PolylineFeatureFromImage_LI_NONDVI_gt.shp")

app.ExecuteAndWriteOutput()

Limitations¶

Since it does not rely on streaming process, take care of the size of input image before launching application.