Stabilization and Georegistration of Aerial Video Over Mountain Terrain by Means of LIDAR Mark Pritt, PhD Lockheed Martin Gaithersburg, Maryland [email protected]Kevin LaTourette Lockheed Martin Goodyear, Arizona kevin.j.latourette@lmc o.com IGARSS 2011, Vancouver, Canada July 24-29, 2011
20
Embed
Stabilization and Georegistration of Aerial Video Over Mountain Terrain by Means of LIDAR Mark Pritt, PhD Lockheed Martin Gaithersburg, Maryland [email protected].
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
· Georegistration is the assignment of 3-D geographic coordinates to the pixels of an image.
· It is required for many geospatial applications: Fusion of imagery with other sensor data Alignment of imagery with GIS and map graphics Accurate 3-D geolocation
· Inaccurate georegistration can be a major problem:
Misaligned GIS
Correctly aligned
3
Solution
· Our solution is image registration to a high-resolution digital elevation model (DEM): A DEM post spacing of 1 or 2 meters yields good results. It also works with 10-meter post spacing.
· Works with terrain data derived from many sources: LIDAR: BuckEye, ALIRT, Commercial Stereo Photogrammetry: Socet Set® DSM SAR: Stereo and Interferometry USGS DEMs
4
· Create predicted images from the DEM, illumination conditions, sensor model estimates and actual images.
· Register the images while refining the sensor model.· Iterate.
Methods
Aerial Video Sensor
Image Plane
Scene
Occlusion
Illumination
Shadow
Predicted Images
5
Methods (cont)
Predicted Image
from DEM
Predicted Image from
Aerial Image
Registration Tie Point
Detections
The algorithm identifies tie points between the
predicted and the actual images by means of NCC
(normalized cross correlation) with RANSAC
outlier removal.
6
· The algorithm uses the refined sensor model as the initial guess for the next video frame:
· The refined sensor model enables georegistration. Exterior orientation: Platform position and rotation angles Interior orientation: Focal length, pixel aspect ratio, principal point
and radial distortion
Methods (cont)
Initial Camera
•Estimate camera model
•Use camera focal length & platform GPS if avail.
Register
•Predict images from DEM and camera
•Register images with NCC
Refine
•Compose registration fcn & camera
•LS fit for better cam estimate
• Iterate
Next Frame
•Register to previous frame
•Compose with cam of prev. frame for init. cam estimate
Iterate
• Iterate for each video frame
Finish
•Trajectory•Propagate geo data from DEM
•Resample images for orthomosaic
7
Example 1: Aerial Motion Imagery
Inputs:
Aerial Motion Imagery over Arizona, U.S.
16 Mpix, 3.3 fps, panchromatic
1/3 Arc-second USGS DEM
Area: 64 km2
Post Spacing: 10 m
8
Example 1 (cont)
Problem: Too shaky to find moving objects
Zoomed to full resolution (1 m)
9
· Outputs: Sensor camera models Images georegistered to DEM Platform trajectory
· We have introduced a new method for aerial video georegistration and stabilization.
· It registers images to high-resolution DEMs by: Generating predicted images from the DEM and sensor model; Registering these predicted images to the actual images; Correcting the sensor model estimates with the registration results.
· Processing speed is 1 sec per 16-Mpix image on a PC.· Absolute geospatial accuracy is about 1-2 meters.
We are developing a rigorous error propagation model to quantify the accuracy.
· Applications: Video stabilization and mosacs Cross-sensor registration Alignment with GIS map graphics