Aligning HD map with satellite imagery from Google

#1

Hi,

I have been trying to align the HD map with satellite imagery from Google. I went through this post (https://github.com/nutonomy/nuscenes-devkit/issues/144), and aligned HD map from nuScenes with terrain mode of Google Earth.

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Figure 1: HD map overlay on terrain mode of Google Earth
Figure 2: Terrain mode of Google Earth

However, when I switched to satellite mode of Google Earth, the alignment was lost.

Figure 3: Satellite mode of Google Earth
Figure 4: HD map overlay on satellite mode of Google Earth (Red arrows indicate some areas of misalignment)

I tried to align by hand, the HD map with satellite mode of Google Earth, through scaling and translation. However this was not possible, as aligning in certain part of the map, caused misalignments in other parts of the map.

My eventual goal is to align HD map with satellite imagery from Google Maps. The satellite imagery source for Google Earth and Google Maps are different, meaning that the satellite imagery from these two places themselves, have a misalignment of ~5 meters or greater.

Figure 5: Point ‘A’ marked on satellite imagery from Google Earth
Figure 6: Same point ‘A’ marked on satellite imagery from Google Maps

You can see that the point ‘A’ is exactly at the center of the intersection in Google Earth, whereas the point ‘A’ is not at the center of the intersection in Google Earth. You can also notice that the satellite imagery used between the two are different.
This means that, even if I align HD map with satellite imagery from Google Earth (manually with hand), this alignment wouldn’t work for satellite imagery from Google Maps.

I have been trying to get this work for a week, but in vain.
It would great to know

  1. If you have tried aligning HD maps with satellite imagery and what was the source (Google or Bing or anything else)?
  2. The date of the satellite imagery used by you
  3. Is there any other method that I could use to align
  4. Any other thoughts on this issue

Thanks in advance.

Convert traffic lights locations from global coordinates system to camera coordinate system
#2

Hi. Apologies for the delay. We know that one of our users tried in a very sophisticated manner to match our map to known landmarks on high quality satellite data. We did see some local deformations in the rubbersheet. The reason is that the map used in nuScenes was collected entirely for the purpose of localization by reidentifying certain patterns. The map does not provide any guarantees on global consistency (e.g. through loop closure). The semantic annotations took place on top of this map and are therefore also not necessarily consistent, although they are quite good. I guess if you want to align our map with Google Earth you would also need to go through the same rubbersheeting procedure.
In addition, for the map expansion, we are currently working on a bug fix for a few locations where a different version of the map was used for localization.

#3

Thanks for the detailed reply. I shall try rubbersheeting and see how well I am able to align.