Tiles without data

[jan-tosovsky-cz]

During processing zoom level 12 tiles I encountered several tiles without data. When inspecting these tiles I found their neighbors are also affected, but only partially.

Is it bug or there is lack of data for these areas?

Example tiles without data: https://s3.amazonaws.com/elevation-tiles-prod/terrarium/12/149/1066.png https://s3.amazonaws.com/elevation-tiles-prod/terrarium/12/150/1066.png https://s3.amazonaws.com/elevation-tiles-prod/terrarium/12/1024/1703.png https://s3.amazonaws.com/elevation-tiles-prod/terrarium/12/1034/1690.png https://s3.amazonaws.com/elevation-tiles-prod/terrarium/12/1104/1703.png https://s3.amazonaws.com/elevation-tiles-prod/terrarium/12/1105/1703.png https://s3.amazonaws.com/elevation-tiles-prod/terrarium/12/1129/1703.png https://s3.amazonaws.com/elevation-tiles-prod/terrarium/12/1130/1703.png https://s3.amazonaws.com/elevation-tiles-prod/terrarium/12/1131/1703.png https://s3.amazonaws.com/elevation-tiles-prod/terrarium/12/1132/1703.png https://s3.amazonaws.com/elevation-tiles-prod/terrarium/12/1133/1703.png https://s3.amazonaws.com/elevation-tiles-prod/terrarium/12/1134/1703.png https://s3.amazonaws.com/elevation-tiles-prod/terrarium/12/1135/1703.png https://s3.amazonaws.com/elevation-tiles-prod/terrarium/12/1136/1703.png https://s3.amazonaws.com/elevation-tiles-prod/terrarium/12/1223/1509.png https://s3.amazonaws.com/elevation-tiles-prod/terrarium/12/1245/1504.png https://s3.amazonaws.com/elevation-tiles-prod/terrarium/12/1246/1504.png https://s3.amazonaws.com/elevation-tiles-prod/terrarium/12/1247/1504.png https://s3.amazonaws.com/elevation-tiles-prod/terrarium/12/1248/1504.png https://s3.amazonaws.com/elevation-tiles-prod/terrarium/12/1249/1504.png https://s3.amazonaws.com/elevation-tiles-prod/terrarium/12/1250/1504.png https://s3.amazonaws.com/elevation-tiles-prod/terrarium/12/1251/1504.png

[zerebubuth]

Looks similar to #99. It seems likely that it's the same cause.