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In the Cesium demo here, you have the option to select choose what data you want to view by simple changing where you are reading the data from.

I want the "Satellites" button to only display those with "Satellite" in the id from the CZML file and ignore the rest, currently my code looks like this:

Sandcastle.addDefaultToolbarButton("Satellites", function () {  
    Cesium.CzmlDataSource.load("../SampleData/simple.czml").then(function(dataSource) {
    viewer.clock.multiplier = 1;
    var entity = dataSource.entities.getById("Satellite");

    viewer.dataSources.add(entity);
  });
  viewer.camera.flyHome(0);
});

However when I try this nothing is shown. I also tried just with the Vehicle (only has 1 entity in it and ID is exactly "Vehicle") so I could check if it is getting the data properly however I got this error: "TypeError: Cannot read properties of undefined (reading 'length')" when clicking on the vehicle button

Here is my for the Vehicle section:

Sandcastle.addToolbarButton("Vehicle", function () {
  Cesium.CzmlDataSource.load("../SampleData/Vehicle.czml").then(function(dataSource) {
    viewer.clock.multiplier = 1;

    var entity = dataSource.entities.getById("Vehicle");
    viewer.dataSources.add(entity);
  });
  
  viewer.scene.camera.setView({
    destination: Cesium.Cartesian3.fromDegrees(-116.52, 35.02, 95000),
    orientation: {
      heading: 6,
    },
  });
emackey
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LongestOfJohns
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1 Answers1

1

Here's a corrected Sandcastle demo.

Some issues in the original:

  • You have a bad ID in one "Satellite" instead of "Satellite/Geoeye1", so the entity was not found.

  • You shouldn't pass an individual entity to viewer.dataSources.add(), instead use viewer.entities.add() for this.

  • The most important, often overlooked problem, is the clock was set wrong. These entities exist for a range of time (several years ago when the sample scenario was first created), and they don't exist in the present. Normally when adding a dataSource to the viewer, the clock automatically updates, but in this case adding a single entity does not do that, so the clock shows the current time instead of a time when the entity exists. There are several ways to fix this, but I chose this one:

    viewer.clock.currentTime = dataSource.clock.startTime;
emackey
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  • Thanks for your response that is very helpful. Is there any way to rather than select by a specific ID, select them so that all entities with "Satellite" in the ID are loaded? – LongestOfJohns Jun 13 '22 at 08:31
  • In the load callback, you can filter the list with `dataSource.entities.values.filter(e => e.id.startsWith("Satellite"))`. Iterate through that array, and add each entity to the viewer. – emackey Jun 17 '22 at 21:37