How to retrieve altitude for multiple selected thumbs?

[lippe]

How do retrieve the altitude for multiple selected thumbs? The Geo tag panel can't do this. i cant find a batch command.

[vlad]

Hi Lippe, I don't understand your question. Are you talking about previously geotagged images? Multiple images ca have multiple altitudes, can't they?

[Hert]

I've added a Batch command for this in the next update.

[vlad]

Sorry if I'm being thick, but what exactly will it do?

[Hert]

Vlad, it will read the coordinates (lat/lng) and find the matching altitude and do that for every image that is in the batch.

[vlad]

Oh, I see. I'm just curious what's the typical use case for initially having the correct coordinates (lat/long) filled in but not the matching altitude.

[Hert]

I can only assume, but I think in combination with GPX files or with GPS recording cameras that record lat/lng but not altitudes

[snowman1]

Additionally to this use case, my understanding is that whilst GPS is quite accurate (given enough satelites in view) for lat/long, it is NOT very accurate in calculating altitude*. Therefore if you are concerned about the altitude it is desirable to replace the GPS-calculated altitude with one looked up on a database by lat/long**. You can check this yourself by comparing the altitude given by a GPS track with those on an Ordnance Survey map in the UK or similar map elsewhere - then replace the GPS altitudes with looked-up altitudes*** and check again.

*I don't know enough about the operation of GPS to know why this is the case, though I do know the system is so finely balanced that the clocks on the satelite - whose timings appear on the signal and are critical to the lat/long calculations - have to be adjusted regularly to account for their running at a slightly different speed due to the effect of relativity on time of satelite altitude / gravity. Otherwise the location would be very inaccurate! That's some system!

** Be aware that on a very steep slope, an error in the GPS location of, say, 10m in lat/long - not unusual if theere aren't many satelites in view - could give an error of maybe 15m in altitude. In the same way these errors can lead to inaccuracies in distance travelled, especially if you are moving at slow speed. GPS is amazing but you can't always take its inferences at face value!

*** various utilities can do this.

HTH

[vlad]

Hi Snowman, thanks for the explanations - the GPS system is surely interesting. I wonder if the same considerations (w.r.t. altitude precision) apply to Glonass (the GPS alternative).

[lippe]

I can only assume, but I think in combination with GPX files or with GPS recording cameras that record lat/lng but not altitudes

My device, a normal GPS for the car, is recording the altitudes, but in some situations, there is a deviation.

Additionally to this use case, my understanding is that whilst GPS is quite accurate (given enough satelites in view) for lat/long, it is NOT very accurate in calculating altitude*

In city's where the there is no clear signal to 4 satellites, the looked up will do a better job.

I wonder if the same considerations (w.r.t. altitude precision) apply to Glonass (the GPS alternative).

I think the Glonass system is comparable with the GPS with the same altitude precision. Both doing better than the Galileo that is still not operational.

[lippe]

I've added a Batch command for this in the next update.

Hert, thank you. This will be more convenient. There is however a limit for number of altitude requests in a time frame. I hope this will not cause problems.

[Stubb]

I've added a Batch command for this in the next update.

Where do I find this batch command? I see "GEO Reverse Lookup Files" but not altitude.

[Hert]

It should be there...

LookupAltitude.png (40.9 KiB) Viewed 6184 times

[Stubb]

How do I get this menu to appear? Thanks!

[Hert]

Click the plus button that you see upper right in the screenshot