dense dsms from stereo imagery

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Dense DSMs from Stereo Imagery

Dr. Philippe SimardPresidentSimActive Inc.

About SimActive

Founded in 2003, SimActive is the developer of Correlator3D™ software, a patented end-to-end photogrammetry solution

SimActive has been selling Correlator3D™ to leading mapping firms and government organizations around the world

Correlator3D™ is the fastest commercial software to perform DSM generation

DSM DTM Mosaic 3D Features

Correlator3D™ Software

DSM Generation

EO Refinement

Mosaic Creation

DEM Editing

Orthorectification

DTM ExtractionMicrosoft Ultracam

Applanix DSS

DiMAC

Intergraph Z/I DMC

VM A3 Mosaic Editing

PROCESSING MODULESIMAGERY

ADS80

Scanned Films

Aerial

GeoEye

ALOS Prism

Cartosat-1

Worldview

Quickbird

Ikonos

SPOT

Satellite

Feature Extraction

DSM Generation

A Digital Surface Model (DSM) is a representation of ground topography

Main Processing Steps: 1. Correlation 2. Triangulation

Bottom-up approach

What is it?

DSM Example

TriangulationCorrelation

Focal point

Image 1 Image 2

Epipolar

Traditional approach: How does it work?

DSM Generation

DSM

What is it?

A dense DSM has a grid post spacing approaching the ground sampling distance (GSD) of the input imagery

Dense DSM Generation

SimActive has just released its next generation DSM engine capable of producing dense DSMs

Dense DSM

Challenges

1. Correlation

2. Sensitivity

3. Density

Process more difficult

Radiometry differences between images Camera calibration Exterior orientation

More points leads to longer processing time

For dense DEM generation

Bottom-Up Derive solution

Feature-Based High density in

some areas only

CPU Few cores

Comparison

Traditional Top-Down

Test solutions

Grid-Based High density in all

areas

GPU Hundreds of cores

SimActive

Focal point

Image 1 Image 2

Top-Down

Idea: test solutions and check whether they solve the correlation problem

Grid-Based

Grid-based DEM is dense everywhere

No interpolation

Correlation performed on all points in the grid

Adjacent solutions assist each other

GPU

Possible Solutions Processing ResultsP11

P21

... Pn1

P12

P22

... Pn2

... P1n

... P2n

...Pnn

GPU Cores

These solutions are processed by the GPU simultaneously

When a match is found, the problem is solved

1 2 3

Many possible solutions are prepared to be tested1

2

3

Results

Resolution: 25 cmAccuracy: 5 cm

Resolution: 15 cmAccuracy: 5 cm

Dense DSMDSM

Benefits

World’s fastest commercially available DSM engine

Direct DSM result removing the need to convert from a point cloud

More points in low texture areas

DSM precision is consistent and homogeneous

Dense DSM

Applications

Dr Philippe SimardPresidentSimActive Inc.psimard@simactive.comwww.simactive.com

Thank You

Official ResellerGroupe SCE IndiaMahesh Nagendra JMobile: +91 9900095741mahesh@sce.co.in