Module Colorisation (PC)
This module attaches the color information from a RGB image to Laser Points.
The RGB Image and the Point Cloud to be colorised are the inputs along with the interior and exterior orientation parameters of the camera. The necessary interior orientation parameters are Focal Length (mm), Pixel Size (um), Principal Point Offsets (pixels) and optionally the Radial Distortion Parameters. The distortion model being used is as follows:
x_d = x_u (1 - dR)
y_d = y_u (1 - dR)
where, dR = K1 * r_u ^ 2 + K2 * r_u ^ 4 + K3 * r_u ^ 6,
r_u ^ 2 = x_u ^ 2 + y_u ^ 2,
x_u, y_u are the undistorted (corrected) image coordinates in mm,
x_d, y_d are the distorted (observed) image coordinates in mm,
K1 is in [mm ^ -2], K2 is in [mm ^ -4], K3 is in [mm ^ -6].
The necessary exterior orientation parameters are the coordinates of the Projection Center and the Cardan angles Omega, Kappa and Alpha. The Cardan angles refer to the following transformation between image coordinates (x_image) and global coordinates (X_Global):
x_image = R_1(omega) * R_2(kappa) * R_3(alpha) * X_Global
[Optional] If the Time Stamp of the RGB Image is given, an acceptable time difference between the points and the image must provided in order to colorise only those points falling that range. If no time is given all points are colorised.
The result is a colorised point cloud.
- Author: HfT Stuttgart (c) 2013
- Specification: grid
- Menu: Imagery|Photogrammetry
Parameters
| | Name | Type | Identifier | Description | Constraints |
|---|
| Input | RGB Image | Grid (input) | rgbImage | RGB Image | - |
| Points to be Colorised | Point Cloud (input) | PC_IN | Points to be Colorised | - |
| Output | Colorised Point Cloud | Point Cloud (output) | PC_OUT | Colorised Point Cloud | - |
| Options | Provide Time stamp of Image? | Boolean | GIVE_TIME | Do you wish to provide the time stamp of Image? | Default: 0 |
| Time stamp of Image | Floating point | IMG_TIME | Time stamp of Image | Default: 0.000000 |
| Time Difference between Image & Points | Floating point | TIME_DIFF | Acceptable Time Difference between Image and Laser Points | Default: 0.000000 |
| Focal Length (mm) | Floating point | F | Focal Length in mm | Default: 0.000000 |
| Pixel Width (um) | Floating point | W | Pixel Width in micro meters | Default: 0.000000 |
| Principal Point Offset in X (pixles) | Floating point | ppX | Principal Point Offset in X | Default: 0.000000 |
| Principal Point Offset in Y (pixels) | Floating point | ppY | Principal Point Offset in Y | Default: 0.000000 |
| Provide Radial Distortion Parameters? | Boolean | GIVE_DISTORTIONS | Do you wish to provide the Radial Distortion Parameters? | Default: 0 |
| K1 | Floating point | K1 | K1 | Default: 0.000000 |
| K2 | Floating point | K2 | K2 | Default: 0.000000 |
| K3 | Floating point | K3 | K3 | Default: 0.000000 |
| Projection Centre - X | Floating point | Xc | Projection Centre | Default: 0.000000 |
| Projection Centre - Y | Floating point | Yc | Projection Centre | Default: 0.000000 |
| Projection Centre - Z | Floating point | Zc | Projection Centre | Default: 0.000000 |
| Omega | Floating point | omega | Rotation Angle | Default: 0.000000 |
| Kappa | Floating point | kappa | Rotation Angle | Default: 0.000000 |
| Alpha | Floating point | alpha | Rotation Angle | Default: 0.000000 |
Command-line
Usage: saga_cmd imagery_photogrammetry 1 -rgbImage <str> -PC_IN <str> [-GIVE_TIME <str>] [-IMG_TIME <str>] [-TIME_DIFF <str>] [-F <str>] [-W <str>] [-ppX <str>] [-ppY <str>] [-GIVE_DISTORTIONS <str>] [-K1 <str>] [-K2 <str>] [-K3 <str>] [-Xc <str>] [-Yc <str>] [-Zc <str>] [-omega <str>] [-kappa <str>] [-alpha <str>] [-PC_OUT <str>]
-rgbImage:<str> RGB Image
Grid (input)
-PC_IN:<str> Points to be Colorised
Point Cloud (input)
-GIVE_TIME:<str> Provide Time stamp of Image?
Boolean
Default: 0
-IMG_TIME:<str> Time stamp of Image
Floating point
Default: 0.000000
-TIME_DIFF:<str> Time Difference between Image & Points
Floating point
Default: 0.000000
-F:<str> Focal Length (mm)
Floating point
Default: 0.000000
-W:<str> Pixel Width (um)
Floating point
Default: 0.000000
-ppX:<str> Principal Point Offset in X (pixles)
Floating point
Default: 0.000000
-ppY:<str> Principal Point Offset in Y (pixels)
Floating point
Default: 0.000000
-GIVE_DISTORTIONS:<str> Provide Radial Distortion Parameters?
Boolean
Default: 0
-K1:<str> K1
Floating point
Default: 0.000000
-K2:<str> K2
Floating point
Default: 0.000000
-K3:<str> K3
Floating point
Default: 0.000000
-Xc:<str> Projection Centre - X
Floating point
Default: 0.000000
-Yc:<str> Projection Centre - Y
Floating point
Default: 0.000000
-Zc:<str> Projection Centre - Z
Floating point
Default: 0.000000
-omega:<str> Omega
Floating point
Default: 0.000000
-kappa:<str> Kappa
Floating point
Default: 0.000000
-alpha:<str> Alpha
Floating point
Default: 0.000000
-PC_OUT:<str> Colorised Point Cloud
Point Cloud (output)