Add sdf param to skip GetGeoRef call when loading DEMs

[adityapande-1995]

Partially resolves #2881

This adds a sdf tag <skipGeoRef> to skip GetGeoRef call and stops it from spamming the console with error msgs. Added extra functions to maintain ABI. Currently this works for gzserver, and gzclient will still throw the same errors.

Testing

This same test file (#2881 (comment)) should not throw any more errors, with a slight modification :

<heightmap>
    <uri>file://dem_neg.tif</uri>
    <size>80.078 80.078 5</size>
    <skipGeoRef>true</skipGeoRef>
</heightmap>

The problem

The chain of function calls is as follows :

Dem.cc::GetGeoRef() --> This function is spamming the error, need to skip it based on an sdf flag.
  |
Dem.cc::Load()
  |
HeightMapDataLoader::LoadDEMAsTerrain()
 |
HeightMapDataLoader::LoadTerrainFile()
 |
HeightMapShape::LoadTerrainFile() --> This has access to the sdf element

Solution 1

This means the sdf flag has to be trickled down without affecting ABI. I could create copies of these functions with different names and have them called by the lowest level LoadTerrainFile() based on the sdf flag.

Issues :

• This makes it difficult to implement in gzclient though, as it does not have access to the sdf element.
• The code just looks unnecessarily complicated with the extra functions.

Solution 2

We could have a service that is advertising a "global" flag that would speficy whether we should run the GetGeoRef function. This would mean the code would be cleaner and changes would be applied to gzclient as well, but it would apply to ALL heightmaps.

[adityapande-1995]

The error seems to be gone in the latest Gazebo Garden, closing this PR for now.