Rotation Computation

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Rotation Computation

Rotation Computation

TerraPhoto uses three angles to define the rotation of airborne images: heading, roll, and pitch. The angles are stored in the image list and displayed to the user as degree values where:

heading zero is aircraft nose pointing north, increases clockwise

roll zero is wings horizontal, increases left wing up

pitch zero is nose horizontal, increase nose up

Three angles alone is not enough to fully define the rotation of an image. The order of rotation needs to be specified as well. TerraPhoto supports six different rotation orders. Attitude computation in the TerraPhoto Settings contains a list for selecting which order to use. This order must match the order in which input data was generated (normally the input trajectory). The standard order of IMU systems is TerraPhoto’s Heading pitch roll order setting.

Angle values heading 30.0, roll 8.0 and pitch 3.0 degrees would result in the following rotation matrices going from camera image to world coordinate system:

Heading roll pitch

0.85759730   0.50562269   0.09419428

-0.49513403   0.86119667  -0.11481545

-0.13917310   0.05182663   0.98891094

Heading pitch roll

0.86123918  0.49931477    0.09461413

-0.48882612  0.86483855   -0.11446973

-0.13898237  0.05233596    0.98891094

Roll pitch heading

0.85395543   0.50144195   0.13898237

-0.49931477   0.86483855  -0.05233596

-0.14644075  -0.02470338   0.98891094

Pitch roll heading

0.85759730   0.49513403   0.13917310

-0.49300685   0.86848042  -0.05182663

-0.14653024  -0.02416692   0.98891094

Roll heading pitch

0.85759730   0.50173923   0.11306906

-0.50000000   0.86483855  -0.04532427

-0.12052744  -0.01766456   0.99255282

Pitch heading roll

0.85759730   0.50000000   0.12052744

-0.48717171   0.86483855  -0.12131781

-0.16489568   0.04532427   0.98526906