Frequently Asked Question
Sun Position and Timestamps - Details
Last Updated 2 years ago
SunPosition ExplainedThe various values of SunPosition in Split-Online provide a measure of how deep into daytime or nighttime an image was acquired. During the day, which is defined as the time after sunrise and before sunset, SunPosition is positive, and during the night (after sunset, before sunrise) it is negative. It crosses zero at sunrise and at sunset.
After crossing zero, the absolute value increases until the midpoint of the day or night, and then decreases back to zero. A value of +5 could mean it has been 5 minutes since sunrise, or it could also mean 5 minutes before sunset. A value of -10 could mean it has been 10 minutes since sunset, or it could mean 10 minutes until sunrise.
The maximum absolute value will be half the number of minutes between sunrise/sunset. The maximum absolute value changes as the timespan between sunrise and sunset changes during the year.
Three Sources of TimeThe time used to calculate the SunPosition can come from three places:
- System Time: The system time (computer time), exported as Common/CurrentLocalTime
- Channel Time: The system time adjusted to the channel's timezone - if defined, exported as ChannelCurrentLocalTime
- File Time: The time extracted from an image file - when the source of images is a module that reads image files, exported from the module that opens the file (as ExportFileTimeStamp in the screenshot below)
Three Values of SunPositionAs shown in the screenshots below, there are three possible values of SunPosition:
- System value, based on system time and system lat/long, exported as Common/SunPosition
- Channel value, based on the channel time and the channel's lat/long, exported as ChannelSunPosition
- File value, based on the file time and the channel's lat/long, exported from the module that opens the file (as FileSunPosition in the screenshot below)