Is ClampToGround not supported for Billboards in CZML?

Jonathan_Hall · August 5, 2018, 11:06pm

1. A concise explanation of the problem you’re experiencing.

Attempting to add “heightReference” : Cesium.HeightReference.CLAMP_TO_GROUND, to Billboard options in CZML,

TypeError: Cannot read property ‘length’ of undefined

the full error is

TypeError: Cannot read property ‘length’ of undefined

at processProperty (Cesium.js:137465)

at processPacketData (Cesium.js:137603)

at Array.processBillboard (Cesium.js:138107)

at processCzmlPacket (Cesium.js:138685)

at Function.CzmlDataSource._processCzml (Cesium.js:139063)

at loadCzml (Cesium.js:138797)

at Cesium.js:138778

at Promise.then (Cesium.js:1163)

at when (Cesium.js:1026)

at load (Cesium.js:138777)

2. A minimal code example. If you’ve found a bug, this helps us reproduce and repair it.

insert on Line #11: “heightReference” : Cesium.HeightReference.CLAMP_TO_GROUND,

3. Context. Why do you need to do this? We might know a better way to accomplish your goal.

I am trying to animate a GPX tracklog using Billboard entities to represent the '“breadcrumb trail”. A better way night have been to include native support for GPX files in Cesium, if that project by Andre Nunes had ever been merged into master… then I wouldn’t struggle writing code to generate a CzmlDataSource from the GPX XML, which works great until I attempt to ClampToGround.

4. The Cesium version you’re using, your operating system and browser.

Cesium v1.4.8, Windows 7, Chrome

Jonathan_Hall · August 5, 2018, 11:48pm

(NOT “heightReference”, which is usually the proper syntax)

However, the billboard still disappears underground at certain times&places when the GPS Z elevation value is less than the Z value of Cesium World Terrain.