The sat_pos_oled topic published by the MQTT broker gives the position of the active satellite in the form of [x, y] coordinates on the 128px by 64px OLED screen. The mapping appears to be linear from ±180° longitude to 0..127 horizontal pixels and from ±90° latitude to 0..63 vertical pixels.
This requires a map in equirectangular projection.
However, the earth image used as a map appears to be some type of pseudo-cylindrical projection. As a result, the indicated satellite position is inaccurate. The error is small when the satellite is near the centre of the map, over Europe, but is large near the edges. Satellites over North America often appear over completely the wrong side of the continent.
Additionally, the earth image used as a map is cropped, and Antarctica is completely missing. So there are additional errors near the south pole.
The map should be replaced by one that covers the whole ±180° longitude and ±90° latitude space using an equirectangular projection.
The
sat_pos_oledtopic published by the MQTT broker gives the position of the active satellite in the form of [x, y] coordinates on the 128px by 64px OLED screen. The mapping appears to be linear from ±180° longitude to 0..127 horizontal pixels and from ±90° latitude to 0..63 vertical pixels.This requires a map in equirectangular projection.
However, the earth image used as a map appears to be some type of pseudo-cylindrical projection. As a result, the indicated satellite position is inaccurate. The error is small when the satellite is near the centre of the map, over Europe, but is large near the edges. Satellites over North America often appear over completely the wrong side of the continent.
Additionally, the earth image used as a map is cropped, and Antarctica is completely missing. So there are additional errors near the south pole.
The map should be replaced by one that covers the whole ±180° longitude and ±90° latitude space using an equirectangular projection.