Small Wall or Verticle Polygon not rendering properly

[bmckilligan]

-using PolygonGeomety, if the shape is too short in the vertical height, it renders as a triangle
-using WallGeometry, if the shape is too short in the horizontal direction, it won't render

sandcastle example:

---

var viewer = new Cesium.Viewer('cesiumContainer');
var scene = viewer.scene;

var instances = [],
dLong = -0.00001,
dLat = 0.00000001 ,
longitude =-122.95287197,
latitude = 49.16011209,
polyLength = 6,
startElevation = 5,
elevationFrom_m = 5,
elevationTo_m,
deltaElevation = 0,
i = 1,
polyPositions = [],
primitives;

for ( i = 1; i <= 30; i++) {
deltaElevation = 0.05 * i;

elevationTo_m = elevationFrom_m + deltaElevation;

polyPositions = [ Cesium.Cartesian3.fromDegrees(longitude + 0 * polyLength * dLong, latitude + 0 * polyLength * dLat, elevationFrom_m),
Cesium.Cartesian3.fromDegrees(longitude - 1 * polyLength * dLong, latitude - 1 * polyLength * dLat, elevationFrom_m),
Cesium.Cartesian3.fromDegrees(longitude - 1 * polyLength * dLong, latitude - 1 * polyLength * dLat, elevationTo_m),
Cesium.Cartesian3.fromDegrees(longitude + 0 * polyLength * dLong, latitude + 0 * polyLength * dLat, elevationTo_m)];

instances.push( new Cesium.GeometryInstance({
geometry: new Cesium.PolygonGeometry.fromPositions({
positions: polyPositions,
perPositionHeight: true,
vertexFormat: Cesium.PerInstanceColorAppearance.VERTEX_FORMAT
}),
attributes: {
color: Cesium.ColorGeometryInstanceAttribute.fromColor(Cesium.Color.fromRandom({alpha : 1}))
}
}) );

instances.push( new Cesium.GeometryInstance({
geometry: new Cesium.WallGeometry({
positions: [
Cesium.Cartesian3.fromDegrees(longitude, latitude),
Cesium.Cartesian3.fromDegrees(longitude + polyLength * dLong, latitude + polyLength * dLat)],
maximumHeights: [elevationTo_m,elevationTo_m],
minimumHeights: [elevationFrom_m,elevationFrom_m],
vertexFormat: Cesium.PerInstanceColorAppearance.VERTEX_FORMAT
}),
attributes: {
color: Cesium.ColorGeometryInstanceAttribute.fromColor(Cesium.Color.fromRandom({alpha : 1}))
}
}) );
elevationFrom_m = elevationTo_m;
polyLength = polyLength - 0.1;
}

scene.primitives.add( new Cesium.Primitive({
geometryInstances: instances,
appearance: new Cesium.PerInstanceColorAppearance({ flat: true }),
show: true
}));

var center = Cesium.Cartesian3.fromDegrees(longitude, latitude , startElevation),
heading = Cesium.Math.toRadians(0),
pitch = Cesium.Math.toRadians(-20.0),
range = 40.0;

viewer.camera.lookAt(center, new Cesium.HeadingPitchRange(heading, pitch, range));

[hpinkos]

@bmckilligan I don't think a vertical polygon is officially supported. Our PolygonGeometry is really meant for drawing polygons on the ellipsoid surface. @bagnell?
For the wall geometry, I believe we just have to change a threshold value somewhere. I'll take a look at it.
Thanks for reporting this!

[bagnell]

@hpinkos is right. Cesium only supports polygons that conform to the surface of an ellipsoid. For a vertical polygon you would need to create a custom geometry. The issue with the walls has been fixed and will be in the 1.12 release.

[bmckilligan]

I have had pretty good results with polygons defined in the vertical plane so far.

Complex geometries with several thousand points have had some some issues , the attached image is a visualization of soil/mud data in a pond with depth %Solids and %water on the left, and some other material properties measured on the right