Model Articulations "Number" variable

CesiumJS
1

Looking at the Model Articulations example on Sandcastle, I am trying to determine what the values in each number array for the stages represent. Specifically the “Fairing Drop” values. Can someone clarify what these values are? https://sandcastle.cesium.com/index.html?src=CZML%20Model%20Articulations.html&label=CZML

Thanks

2

Welcome to the Cesium community!

You can find this documented here: ModelGraphics - Cesium Documentation

Gets or sets the set of articulation values to apply to this model. This is represented as an PropertyBag , where keys are composed as the name of the articulation, a single space, and the name of the stage.

If you look inside the glTF model you’ll see these names defined as an extension:

{
      "mesh": 5,
      "name": "Fairing1",
      "translation": [
        0,
        -2.7000010013580322,
        3.3499984741210938
      ],
      "extensions": {
        "AGI_articulations": {
          "articulationName": "Fairing"
        }
      },
      "rotation": [
        0,
        0,
        0,
        1
      ],
      "scale": [
        1,
        1,
        1
      ]
    }

And the stages defined:

{
          "name": "Fairing",
          "stages": [
            {
              "name": "Separate",
              "type": "yTranslate",
              "minimumValue": -1000,
              "maximumValue": 0,
              "initialValue": 0
            },
            {
              "name": "Drop",
              "type": "zTranslate",
              "minimumValue": -1000,
              "maximumValue": 0,
              "initialValue": 0
            },
            {
              "name": "Open",
              "type": "xRotate",
              "minimumValue": 0,
              "maximumValue": 180,
              "initialValue": 0
            },
            {
              "name": "Size",
              "type": "uniformScale",
              "minimumValue": 0,
              "maximumValue": 1,
              "initialValue": 1
            }
          ]
        }

You can read more about this glTF extension here: https://github.com/KhronosGroup/glTF/blob/master/extensions/2.0/Vendor/AGI_articulations/README.md.

What kind of project are you working on?

2 Likes
3

Thx a lot @omar, this input helped me quite a lot.
The gltf tools extension (by cesium :)) for VS Code comes in very handy for visualization, see:

image
image1198×728 71.1 KB

Question: Is the AGI_articulation extension still the only way to embed animation into czml files? Or is there by now another way to directly use the animations from the model, i.e.g if it is already shipped with some of them:

image
image1136×556 162 KB

Thx for any insights!

1 Like
4

some more information about the “number” array => time key & value:

articulation_number
articulation_number1633×996 288 KB

5

Can we get confirmation of what these number values mean? What it looks like is the “Fairing Open” articulation starts at 0 seconds into the epoch time and interpolates the degree values linearly from 0 to 120 over 600 seconds.

It doesn’t appear that the seconds value can be fractional. Is this correct?

Also it seems that I could only make an object instantaneously disappear by doing something like:
“SRBs Size”: {
epoch: “2019-06-01T16:00:00Z”,
number: [0, 1, 298, 1, 299, 0, 300, 0],
},

Is this the desired procedure?