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Fix billboard on terrain and Globe.getHeight #4622

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merged 21 commits into from
Dec 26, 2016
Merged

Fix billboard on terrain and Globe.getHeight #4622

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ead79f4
fix_billboardOnTerrain
duvifn Nov 2, 2016
9f7d911
fix Globe.getHeight function
duvifn Nov 3, 2016
156d5bb
compute origin point at the intersection of the surface normal with t…
duvifn Nov 27, 2016
4d12c0e
add to CHANGES.md
duvifn Nov 27, 2016
9f551ab
typos
duvifn Nov 27, 2016
306c276
Merge branch 'master' into fix_billboardOnTerrain
duvifn Dec 5, 2016
74a7de5
cartesian is computed on the ellipsoid surface
duvifn Dec 5, 2016
30e73ff
fix typo
duvifn Dec 5, 2016
7894d20
added Ellipsoid.getSurfaceNormalRayFromZAxis. no tested
duvifn Dec 7, 2016
edfd685
fix Ellipsoid.getSurfaceNormalIntersectionWithZAxis
duvifn Dec 12, 2016
1b4f97d
Merge branch 'master' into fix_billboardOnTerrain
duvifn Dec 12, 2016
23d2fea
factor out sqauredAOverSquaredB
duvifn Dec 13, 2016
dbd917d
add _sqauredAOverSquaredB to the Ellipsoid constructor
duvifn Dec 13, 2016
0947e12
add check if radii.z===0
duvifn Dec 13, 2016
244cc52
remove unused dependency, change sqauredAOverSquaredB to sqauredXOver…
duvifn Dec 13, 2016
9ae322c
Whitespace
pjcozzi Dec 24, 2016
056fc20
Whitespace
pjcozzi Dec 24, 2016
b394335
Style tweak
pjcozzi Dec 24, 2016
1f325e5
Style tweak
pjcozzi Dec 24, 2016
761eda4
Style tweak
pjcozzi Dec 24, 2016
d01196b
fix typo in spec title
duvifn Dec 26, 2016
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11 changes: 10 additions & 1 deletion Source/Scene/Globe.js
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Original file line number Diff line number Diff line change
Expand Up @@ -430,7 +430,16 @@ define([
var cartesian = ellipsoid.cartographicToCartesian(cartographic, scratchGetHeightCartesian);

var ray = scratchGetHeightRay;
Cartesian3.normalize(cartesian, ray.direction);
var surfaceNormal = ellipsoid.geodeticSurfaceNormal(cartesian, ray.direction);

// compute origin point, to account for a case where the terrain is under ellipsoid surface
var minimumHeight = Math.min(defaultValue(tile.data.minimumHeight, 0.0), 0.0);
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@duvifn duvifn Nov 8, 2016 •
edited
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@bagnell , do you think it would be safer to use lower value instead of 0.0 in defaultValue(tile.data.minimumHeight, 0.0)?
for example -11500.0 (taken from here, wikipedia)

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I would use -11500.0. For the lowest resolution terrain tiles, triangle vertices may be near the ellipsoid surface, but the interiors cutting through the ellipsoid will drop to around this height. Is there a reason you didn't use Cartesian3.ZERO? Did you run into precision issues in the triangle intersection test?


// take into account the position height
minimumHeight -= cartographic.height;

var minimumHeightVector = Cartesian3.multiplyByScalar(surfaceNormal, minimumHeight - 1.0, scratchGetHeightIntersection);
Cartesian3.add(cartesian, minimumHeightVector, ray.origin);

var intersection = tile.data.pick(ray, undefined, undefined, false, scratchGetHeightIntersection);
if (!defined(intersection)) {
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12 changes: 9 additions & 3 deletions Source/Scene/QuadtreePrimitive.js
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Expand Up @@ -632,9 +632,15 @@ define([

if (mode === SceneMode.SCENE3D) {
var surfaceNormal = ellipsoid.geodeticSurfaceNormal(data.position, scratchRay.direction);
// subtract by earth minor axis radius, to account for a case where the terrain is under ellipsoid surface - is that OK or should I use lower value (maybe -11500.0 which appears some lines bellow)?
var radiusLengthVector = Cartesian3.multiplyByScalar(surfaceNormal, ellipsoid.minimumRadius, scratchPosition);
Cartesian3.subtract(data.position, radiusLengthVector, scratchRay.origin);

// compute origin point, to account for a case where the terrain is under ellipsoid surface
var minimumHeight = Math.min(defaultValue(tile.data.minimumHeight, 0.0), 0.0);

// take into account the position height
minimumHeight -= data.positionCartographic.height;

var minimumHeightVector = Cartesian3.multiplyByScalar(surfaceNormal, minimumHeight - 1.0, scratchPosition);
Cartesian3.add(data.position, minimumHeightVector, scratchRay.origin);
} else {
Cartographic.clone(data.positionCartographic, scratchCartographic);

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