GeneratePlyFile - Ply 3D files generation¶

Generate a 3D Ply file from a DEM and a color image.

Detailed description¶

The application converts an image containing elevations into a PLY file, which is a file format to store 3D models. This format is adpated for visualization on software such as MeshLab [2] or CloudCompare [3]

This application is part of the stereo reconstruction framework. The input data can be produced by the application DisparityMapToElevationMap.

There are two types of supported input images:

A DEM image, with a ground projection, containing elevation values. Each elevation value can be considered as a 3D point.
A 3D grid image, containing 5 bands (the first 3 are the 3D coordinates of each point, the 5th is a validity mask where valid values are larger or equal to 1)

The user shall also give a support image that contains color values for each 3D point. The color values will be embedded in the PLY file.

Parameters¶

This section describes in details the parameters available for this application. Table [1] presents a summary of these parameters and the parameters keys to be used in command-line and programming languages. Application key is GeneratePlyFile .

[1]	Table: Parameters table for Ply 3D files generation.

Parameter Key	Parameter Name	Parameter Type
indem	The input DEM image	Input image
mode	Conversion Mode	Choices
mode dem	DEM	Choice
mode 3dgrid	3D grid	Choice
map	Output Cartographic Map Projection	Choices
map utm	Universal Trans-Mercator (UTM)	Choice
map lambert2	Lambert II Etendu	Choice
map lambert93	Lambert93	Choice
map wgs	WGS 84	Choice
map epsg	EPSG Code	Choice
map.utm.zone	Zone number	Int
map.utm.northhem	Northern Hemisphere	Boolean
map.epsg.code	EPSG Code	Int
incolor	The input color image	Input image
out	The output Ply file	Output File name
inxml	Load otb application from xml file	XML input parameters file
outxml	Save otb application to xml file	XML output parameters file

The input DEM image: The image should be either a projected DEM or a 3D grid containing 3D point coordinates and a validity mask.

Conversion Mode Available choices are:

DEM: DEM conversion mode (the projection information of the DEM is used to derive the X and Y coordinates of each point).
3D grid: 3D grid conversion mode.

Output Cartographic Map Projection: Parameters of the output map projection to be used. Available choices are:

Universal Trans-Mercator (UTM): A system of transverse mercator projections dividing the surface of Earth between 80S and 84N latitude.

Zone number: The zone number ranges from 1 to 60 and allows defining the transverse mercator projection (along with the hemisphere).

Northern Hemisphere: The transverse mercator projections are defined by their zone number as well as the hemisphere. Activate this parameter if your image is in the northern hemisphere.

Lambert II Etendu: This is a Lambert Conformal Conic projection mainly used in France.
Lambert93: This is a Lambert 93 projection mainly used in France.
WGS 84: This is a Geographical projection.
EPSG Code: This code is a generic way of identifying map projections, and allows specifying a large amount of them. See www.spatialreference.org to find which EPSG code is associated to your projection;.

EPSG Code: See www.spatialreference.org to find which EPSG code is associated to your projection.

The input color image: If the color image has 4 bands it will be interpreted as Red, Green, Blue, NIR. In other cases, only the first one is used (gray scale colors). The color values are expected in the range 0 - 255, and will be embedded with each 3D point of the PLY file.

The output Ply file: The output Ply file will contain as many 3D points as pixels in the input DEM.

Load otb application from xml file: Load otb application from xml file.

Save otb application to xml file: Save otb application to xml file.

Example¶

To run this example in command-line, use the following:

otbcli_GeneratePlyFile -indem image_dem.tif -out out.ply -incolor image_color.tif

To run this example from Python, use the following code snippet:

#!/usr/bin/python

# Import the otb applications package
import otbApplication

# The following line creates an instance of the GeneratePlyFile application
GeneratePlyFile = otbApplication.Registry.CreateApplication("GeneratePlyFile")

# The following lines set all the application parameters:
GeneratePlyFile.SetParameterString("indem", "image_dem.tif")

GeneratePlyFile.SetParameterString("out", "out.ply")

GeneratePlyFile.SetParameterString("incolor", "image_color.tif")

# The following line execute the application
GeneratePlyFile.ExecuteAndWriteOutput()

Limitations¶

The input DEM image has to entirely fit into memory.

Authors¶

This application has been written by OTB-Team.