Issue with 'Height from terrain' measurement

[tdipisa]

Description

Height from terrain measure in 3D mode doesn't seem to report the correct height in certain cases

How to reproduce

• Open this map
• Switch to 3D mode and activate the Measurement tool
• Activate the Height from terrain measurement
• Do a measurement with and without the Genova 3D layer active in TOC

Expected Result

The measurement tool should always provide the correct measurement value and properly handle corner cases by notifying the user if necessary (e.g. a measurement cannot be performed on a certain location for a specific reason).

Current Result

With mesh active in TOC

With mesh not active in TOC (same location)

• Not browser related

Browser info

(use this site: https://www.whatsmybrowser.org/ for non expert users)

Browser Affected	Version
Internet Explorer
Edge
Chrome
Firefox
Safari

Other useful information

[tdipisa]

Connected to #9548

It seems the native function of Cesium pickPosition has some problems that has not completely resolved yet (see here). After some quick tests I think we could only partially mitigate it by applying one of the following:

• Option 1) try to improve the pickPosition detection by selecting only specific feature for this purpose and excluding feature that will return wrong position such as GroundPrimitive or GroundPolylinePrimitive (It seems to work but there are still some edge cases eg intersection of a 3D tiles feature and terrain)
• Option 2) use only drillPickFromRay to intersect features in combination with globe pick. Note that drillPickFromRay is a private function and it’s not documented in the official Cesium documentation. (Seems to work but worried about performance and private method)
• Option 3) Evaluate if other picking options are available in Cesium (Not found other options at the moment)

Then we have to:

• Ensure that dynamic billboard and primitive are not included in the pick workflow of drawing and modify in Cesium. They should be added inside the _getObjectsToExcludeOnPick function