medium format digital cameras: standards and specifications for calibration and stability analysis
DESCRIPTION
Medium Format Digital Cameras: Standards and Specifications for Calibration and Stability Analysis. A. F. Habib Digital Photogrammetry Research Group http://dprg.geomatics.ucalgary.ca Department of Geomatics Engineering University of Calgary, Canada. Introduction. - PowerPoint PPT PresentationTRANSCRIPT
CRSS/ASPRS 2007
Medium Format Digital Cameras:Standards and Specifications for
Calibration and Stability Analysis
A. F. HabibDigital Photogrammetry Research Group
http://dprg.geomatics.ucalgary.ca
Department of Geomatics EngineeringUniversity of Calgary, Canada
2CRSS/ASPRS 2007
Introduction
3CRSS/ASPRS 2007
• Classification of digital cameras (photogrammetric perspective):– Line Cameras (ADS 40)– Large format digital frame cameras (??)– Multi-head digital frame cameras (DMCTM, UltrCam,
DiMAC 2.0)– Medium-format Digital Cameras (MFDC):
• Mass-produced MFDC for mapping purposes (DSS, DiMAC Light)
• MFDC for mapping purposes from data providers (DAC 101)• Amateur medium format digital cameras (AMFDC)
Operational Photogrammetric Systems
4CRSS/ASPRS 2007
MFDC from Data Providers
• DAC 101: Camera assembled by Selkirk Remote Sensing• The camera utilizes a 60mm Rollei lens with a Rodenstock Apo-Sironar shutter and a
22 megapixel digital back (5440x4080 Imacon Ixpress 132 Digital Back with 9µm pixel size)
5CRSS/ASPRS 2007
Amateur Medium-Format Digital Cameras
SONY 717
Kodak 14n
Canon EOS 1D
AMFDC
6CRSS/ASPRS 2007
Large Format Analog Cameras (LFAC)
WILD RC10
7CRSS/ASPRS 2007
SONY DSC F717
Medium Format Digital Cameras (AMFDC)
8CRSS/ASPRS 2007
MFDC: Relevant Questions
• Is the use of amateur MFDC in mapping applications a temporary or permanent phenomenon?
• How to develop meaningful standards for evaluating the outcome from the calibration procedure?
• How to develop meaningful standards for evaluating the stability of the involved camera?
• Is there a flexibility in choosing the stability analysis tool, which is commensurate with the geo-referencing procedure to be implemented for this camera?
9CRSS/ASPRS 2007
• Regulating the use of imaging systems in mapping applications can be done through either:– Having a government body (third party) responsible for
the evaluation/calibration of the imaging systems.• Widely adopted for analog cameras (USGS, NRCAN).
– Certifying the imaging systems.• Suitable for digital imaging systems intended for mapping
applications (DMCTM, ADS 40, UltrCam, DiMAC, DSS, etc.).
– Transferring the responsibility to the data provider after establishing a set of standards and specifications.
• Appropriate for AMFDC and MFDC from data providers.– Calibration, stability analysis, achievable accuracy.
Standards and Specification Philosophy
10CRSS/ASPRS 2007
Indoor Calibration Test Field
11CRSS/ASPRS 2007
Indoor Calibration Test Field
12CRSS/ASPRS 2007
Indoor Calibration Test Field
13CRSS/ASPRS 2007
Indoor Calibration Test Field
14CRSS/ASPRS 2007
Tested Cameras (Example)
15CRSS/ASPRS 2007
Tested Cameras (Example)
16CRSS/ASPRS 2007
Data Acquisition
17CRSS/ASPRS 2007
Calibration Images
Center High & Low
18CRSS/ASPRS 2007
Calibration Images
Left High & Low
19CRSS/ASPRS 2007
Calibration Images
Right High & Low
20CRSS/ASPRS 2007
Calibration Specifications
• Variance component of unit weight:– Tier I < 1 Pixel– Tier II < 1.5 Pixels– Tier III < N/A Pixels
• No correlation should exist among the estimated parameters
• Standard deviations of the estimated IOP parameters (xp, yp, c):– Tier I < 1 Pixel– Tier II < 1.5 Pixels– Tier III < N/A
21CRSS/ASPRS 2007
cIcII
P.C.I
P.C.II
Original Image Grid PointsDistortion-free Grid Points using IOPI
Bundle IBundle II
Distortion-free Grid Points using IOPII
Side ViewTop View
Stability Analysis: Proposed Approach
≡?
22CRSS/ASPRS 2007
• Method 1: Zero Rotation (ZROT)– Same perspective center (no shift allowed)– Parallel image coordinate systems (no rotation allowed)
P.C.
cI
cII
Offset
II
I
ccx2
2x
Ray from Bundle I
Ray from Bundle II
12 x
ccxII
I
Original Image Points
Distortion-free Grid Point using IOPI
Distortion-free Grid Point using IOPII
Projected Grid Point of IOPII
Stability Analysis: Proposed Approach
23CRSS/ASPRS 2007
• Method 2: Rotation (ROT)– Same perspective center (no shift allowed)– Rotation allowed
P.C. (0, 0, 0)
pI (xI, yI,-cI)
pII (xII, yII,-cII)
R (, , )
SpatialOffset
Original Image Points
Distortion-free Grid Point using IOPI
Distortion-free Grid Point using IOPII
Projected Grid Point of IOPII
Stability Analysis: Proposed Approach
24CRSS/ASPRS 2007
• Method 3: Single Photo Resection (SPR)– Object space comparison– Spatial and rotational offsets permitted
cI
P.C.Ic
II P.C.II
Bundle IBundle II
Offset
Original Image Points
Distortion-free Grid Point using IOPI
Distortion-free Grid Point using IOPII
Back-projected Object Points
Stability Analysis: Proposed Approach
25CRSS/ASPRS 2007
Stability Specifications
• The similarity measure (RMSE offset) value is computed to express the degree of similarity between the bundles from two sets of IOPs.
• The cameras must meet the following specifications to be deemed stable. – Tier I < 1 Pixel– Tier II < 1.5 Pixels– Tier III : N/A
• A software is available for the calibration and stability analysis procedures.
26CRSS/ASPRS 2007
• Can the stability analysis be used for evaluating the equivalency of different distortion models?– Appropriate distortion models.
• Should the standards for the calibration and stability analysis be expressed in terms of image or object space units?
• What is the achievable accuracy from MFDC?– Geo-referencing method (GCP, GNSS-assisted,
GNSS/INSS).– Number of tie points.
• What are the applications most suited for MFDC?– Small blocks, in combination with LiDAR systems, in
combination with high resolution satellite scenes.
MFDC: Relevant Questions
27CRSS/ASPRS 2007
MFDC & Aerial Mapping
• Kodak DCS-14n• CMOS (4536x 3024)• 50 mm Zeiss lens • Pixel size: 7.9x7.9 µm• 12 Photos• Flying height: 1200 m• GSD: 0.20 meters
28CRSS/ASPRS 2007
Federal University of Parana, Brazil
MFDC & Aerial Mapping
29CRSS/ASPRS 2007
Number of Check Points Mean(m)
Standard dev. (m)
RMSE(m)
17 Signalized
Targets
X 0.055 0.147 0.157
Y 0.210 0.113 0.238
Z 0.170 0.311 0.355
28 Natural Targets
X 0.231 0.343 0.413
Y 0.201 0.141 0.246
Z -0.033 0.693 0.694
MFDC & Aerial Mapping
Root Mean Square Error Analysis
30CRSS/ASPRS 2007
Orthophoto generated for Kodak (left) and RC10 (right) imagery
MFDC & Aerial Mapping
31CRSS/ASPRS 2007
IKONOS stereo-pair
DSSthree six-image blocks with GPS position of
exposure stations
LIDAR data
up
middle
down
MFDC, LiDAR & Satellite Scenes
32CRSS/ASPRS 2007
Lower Block
DSS: Lower Block Lower LIDAR Scan
Experimental Results: Dataset
33CRSS/ASPRS 2007
0.000
5.000
10.000
15.000
20.000
25.000
30.000
35.000
0 1 2 3 4 5 6 7 8 9 10 15 40
Number of Control Points
RM
SE, m
NO Frames
Frame
GPS
Lines(45)
Lines (138)
Patches (45)
Patches (139)
N/A
MFDC, LiDAR & Satellite Scenes