[Elphel-support] [Elphel-support-Eyesis] GPS Heading

[support-list-eyesis]

>How come I am receiving "Zero" for heading from the GPS on Eyesis 4Pi? 
> How can I resolve this? 
>Thanks! 
> 
GPS receiver does not provide heading data. When you use a hand-held GPS receiver, it calculates your heading when you move, comparing positional data along your way, so that is calcualted, derivative data. Real time systems used for navigation can only use half of the recorded data - samples that happened in the past. When you process recorded images, you do not have such limitation, so post-processing can achieve better results that on-the-fly calculated heading. This is why we do not do it in the camera but rather record positional data in the log (and in the Exif of each frame).

The GPS heading fileds in the Exif in the camera are used for different purpose -  and not for the Eyesis camera (Eyesis camera modules share all the code with the general purpose model 353 units). These Exif fields are were used by the camera to provide raw data from the magnetometer (compass) if it exists in the system. But even in that case it can not be used as real "heading" of the camera (it has to be post-processed and is in combination with inertial data).

Andrey