Camera parameter convert from Cesium

[gisjiashu]

Hi ,

In Cesium app, the camera parameters contains Position(x, y, z), Heading, Pitch, and Roll.

I just found similiar function in iTwinjs which is LookAt funtion, but don't know how to convert Cesium parameters to iTwinjs.

Ps: I debug it using lookAtGlobalLocation(eyeHeight: number, pitchAngleRadians = 0, location?: GlobalLocation, eyePoint?: Point3d), but missing Heading and Roll parameters from Ceisum.

Thanks

[gisjiashu]

It seems that camrea need to rotate a angle. But failure while in setting ratotion in view.

[pmconne]

The iTwin.js equivalent of Cesium.HeadingPitchRoll is YawPitchRollAngles.
Here are diagrams illustrating iTwin.js camera parameters.

[gisjiashu]

Is that means excute before viewState.lookAtUsingLensAngle function, should set Rotation first?
The rotation parameter comes from YawPitchRollAngles propoerty.

[bbastings]

lookAtUsingLensAngle will set the view rotation. The vector from targetPoint to eyePoint becomes view Z, and the upVector determines view Y. Then Y cross Z becomes View X.

YawPitchRollAngles.toMatrix3d could be used if you were going to call Viewport.setRotation and set up all the view parameters yourself according to diagram, not if you're going to call lookAtUsingLensAngle.

[gisjiashu]

In the source code, we just used the pitch angle parameter from Cesium. Cann't set heading angle in the lookAtUsingLensAngle.
Is the vector from targetPoint to eyePoint(iTwin.js) means Heading(Cesium) angle?

[bbastings]

Is the vector from targetPoint to eyePoint(iTwin.js) means Heading(Cesium) angle?

They aren't directly comparable, one is a Vector3d and the other is an angle in radians...

You could do something like HeadingPitchRoll -> YawPitchRoll -> toMatrix3d, and use Matrix3d.getColumn(2) to compute a targetPoint, etc.