I'm having an issue with displaying a 2-d image graphic on a route to show direction at each waypoint. I started using a billboard but since it was always viewport facing it would get distorted when looking from certain angles. My current thoughts are to have a RectangleGraphic or BoxGraphic with the ImageMaterial and determine the rotation/orientation between the two points on the route. This works but there is no scaling for these graphics.
I am currently going to determine the camera distance and attempt to update the dimensions on the BoxGraphic using a CallbackProperty. Other option I have thought would be to create a simple 3-d model which could be drawn & scaled at each point.
My question is two-fold. Has scaling of the geometry objects been done before? What would perform better, a CallbackProperty on the BoxGraphics or a simple 3-d model?
Thanks
hannah
August 16, 2016, 1:08pm
2
Hello,
I think using a Billboard was the right way to go. Try using the VelocityVectorProperty to align the billboard with the route direction.
See the documentation for a code example: http://cesiumjs.org/Cesium/Build/Documentation/VelocityVectorProperty.html?#VelocityVectorProperty
Best,
Hannah
Thanks for the reference, I was working off 1.21 and didn't notice this was recently added.
I have updated to 1.24 and attempted to set this but the image still doesn't follow the route, below is an example I wrote in the Sandcastle:
var viewer = new Cesium.Viewer('cesiumContainer');
var p1 = Cesium.Cartesian3.fromRadians(-1.9551931146066619, 0.6355705619064884, 0.0);
var position = new Cesium.SampledProperty(Cesium.Cartesian3);
viewer.entities.add(new Cesium.Entity({#bbbbbb ")
When I calculate the vector between the two points as a unit vector and set that to the aligned axis I was able to get the desired results.
The VelocityVectorProperty comments pointed me in the right direction, am I using that property incorrectly?
I was able to get VelocityVectorProperty to work when I adjusted the point times to be 1/60 step apart. It got me the same results, the direction of my icon down is slightly skewed from the line
hannah
August 17, 2016, 2:02pm
6
Glad you were able to figure it out.https://github.com/AnalyticalGraphicsInc/cesium/issues/2487
If you didn’t want to use a Billboard because of this issue, my other suggestion would be to use a simple glTF model and give it a minimumPixelSize so it stays the same size on the screen as you zoom out.
Check out this example: http://cesiumjs.org/Cesium/Apps/Sandcastle/index.html?src=3D%20Models.html&label=Showcases
Best,
Hannah
Thanks Hannah!
I have implemented what i needed using a simple plane gITF model and got the desired results. Thanks for all your help