Elevation of terrain

[juanmajr93]

Hi, I have a new question about how can I get a elevation of terrain. Now I am using this function:CreateGroundFromHeightMap() and I use a png as parameter. However, I dont get the accuracy that I would like having. I have 1 height by each 2meters so I consider that I should use this data to calculate the height of terrain instead of the intensity of color. Do you know how could I do it?

 

Thanks

JMJR

[jerome]

I don't really get what you mean ...  http://doc.babylonjs.com/classes/2.5/MeshBuilder#static-creategroundfromheightmap-name-url-options-scene-rarr-groundmesh-classes-2-5-groundmesh-

[Dad72]

exemple elevation:

http://www.babylonjs.com/Scenes/Worldmonger/index.html

multi-texture:

http://doc.babylonjs.com/extensions/Terrain

[juanmajr93]

Well I have an elevation of terrain in GLOBAL MAPPER, it is a software to load differents type of files. I get this elevation using ortographic information. When I export this to png for using in BabylonJS I dont get the same accuracy. My question is if you know other way to elevate terrain using height data directly instead of image.

Theese are the captures of elevation of terrain and heigh map in GLOBAL MAPPER

 

The format of the height's file is:

Latitud, Longitud, Altura

431001,4183099,433.692
431001,4183097,433.408
431001,4183095,433.208
431001,4183093,433.115
431001,4183091,432.998

Thanks

JMJR

[jerome]

yes, you can.

Just create an updatable ground (not a ground from heightmap) and then update each vertex y coordinate accordiling to your altitude data. You'll find plenty of examples in this forum about how to do this.

[juanmajr93]

Hi again, finally I got the acuracy that I wanted exporting an image with png 24bits format. I solved this problem. However I have the next question. How could I get the height coordinate of ground after heightmap is applied?

Thanks and HAPPY NEW YEAR!!

[jerome]

http://doc.babylonjs.com/classes/2.5/GroundMesh#getheightatcoordinates-x-z-rarr-number

[juanmajr93]

yes this function is exactly that I need. However this is my code and it doesnt work...

var ground = BABYLON.Mesh.CreateGroundFromHeightMap("ground", "assets/textures/map.png", _width, _height, 1000, 0, 150, scene, false);
       
console.log(ground.getHeightAtCoordinates(0, 0));

 

[juanmajr93]

I am confused because when I print the number of vertices i get 0...

console.log(ground.getTotalVertices());

 

[jerome]

you need to wait for your ground to be created once the heightmap is downloaded... so call any method on a heighmap terrain only in the callback function

http://doc.babylonjs.com/classes/2.5/MeshBuilder#static-creategroundfromheightmap-name-url-options-scene-rarr-groundmesh-classes-2-5-groundmesh-

have a look at the parameter "onReady"

[juanmajr93]

ok thanks jerome but how can i use this callback coud you show me and example?

[jerome]

something like this : 

var callbackFunction = function(mesh) {
    var h = mesh.getHeightAtCoordinates(x, z);
};

var options = {width: width, height: height, subdivisions: subdivisions, minHeight: 0,  maxHeight: 60, onReady: callbackFunction};
var ground = BABYLON.MeshBuilder.CreateGroundFromHeightMap("ground", "http://www.babylonjs-playground.com/textures/heightMap.png", options, scene);

 

[juanmajr93]

@jerome

This solution is perfect! I have tested it and I get a height. The last question is the follow.  what are all vertices of mesh ?¿width*height ? I wil have to visit all of them and get their height...

 

Thanks!

[juanmajr93]

I have made this iteration:

      var callbackFunction = function(mesh) {
            var vertex_data = BABYLON.VertexData.ExtractFromMesh(mesh);
            var h;    
            for (var i = 0; i < vertex_data.positions.length; i+=3) {
                h = mesh.getHeightAtCoordinates(vertex_data.positions[i],vertex_data.positions[i+1]);
                console.log(h);
            }
        }; 

is it well?

[jerome]

In this case, simply retrieve the vertex positions :

positions = mesh.getVerticesData(BABYLON.VertexBuffer.PositionKind);

positions -> x

positions[i + 1] -> y  (height)

positions[i + 2] -> z

[juanmajr93]

@jerome

yes it is well and I store all vertices of ground to array. However, I can not solve my problem by this way. I have different objects(tubes) and I have to get the height of (x,y) coordinates of ground wich are under this object exactly to set his height. Firstly, I don't know what are the vertices of ground under theese objects. Maybe, I consider that a solution can be use a ray to get the vertex under each point of tubes.... I hope your help

Thanks

[juanmajr93]

I have just solved my problem. I was importing another version of babylonjs to my project and I get strange heights of vertices. I dont know the reason, maybe some update of framework. Now I am using this import:  <script src="http://www.babylonjs.com/babylon.js"></script>

is it always the last version of BabylonJS?

[adam]

You should use the cdn.

http://cdn.babylonjs.com/2-5/babylon.js

http://cdn.babylonjs.com/2-5/babylon.max.js

If you need the preview release:

for production:

https://cdn.rawgit.com/BabylonJS/Babylon.js/master/dist/preview release/babylon.js

for development:

https://rawgit.com/BabylonJS/Babylon.js/master/dist/preview release/babylon.js