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emenegro
Hello.

I am unable to geotag correctly the photos using a KML downloaded from the Google Maps location history converted to GPX using GPSVisualizer.

In HoudahGeo I import the photos from the iPhoto library, which have the correct timestamp and timezone, and then I add the GPS track. Then, in the process tab I see the map, with the correct locations, but the photos geotag wrong, not in the expected locations.

It seems to be a problem with the time in the exported KML but I cannot get the correct geotagging after changing the camera setup, time error, etc. My timezone is CEST (Madrid), but this is an extract of the GPX:

    <trkpt lat="40.4369235" lon="-3.6780876">
      <ele>0.0</ele>
      <time>2014-07-04T15:19:07Z</time> 
   </trkpt>

The timezone is UTC, so, where do I have to apply the correction to match photos and track? Do you had any problem with this workflow?

Thank you so much.
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houdah
Hi!

Timestamps in GPX track logs must be expressed in the UTC time zone. HoudahGeo counts on that.

Please check that the time stamp is correct. I.e. the above should translate to 17:19 in Madrid.

HoudahGeo however needs help to make sense of the time value embedded in your photos. The camera may have recorded a time of 17:19. You to tell HoudahGeo that this is to be understood as 17:19 CET.

A good way to check that the settings are correct is by comparing the time (and date !) HoudahGeo shows for the first photo in your project with the start time of the first track. Both values are expressed in the same time zone. The name of that time zone shows in the top right corner of the HoudahGeo window.

Best,
Pierre Bernard
Houdah Software s.à r.l.
Houdah Software s. à r. l.
https://www.houdah.com

HoudahGeo: One-stop photo geocoding
HoudahSpot: Advanced file search utility
Tembo: Easy and effective file search
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houdah
Hi!

A different thought: what does your track log look like? Are there large gaps?

HoudahGeo expects the track log to be a recording of your movements. It will place your photo between the two track points closest in time to your photo. This only makes sense if not too much time elapsed between the two track points.

You can configure the behavior of automatic geocoding when you select Geocode using GPS data… from the Process menu.

If you only have a few hand-picked locations rather than a continuous track log, you will get better results by providing these as waypoints to HoudahGeo.

Best,
Pierre Bernard
Houdah Software s.à r.l.


Houdah Software s. à r. l.
https://www.houdah.com

HoudahGeo: One-stop photo geocoding
HoudahSpot: Advanced file search utility
Tembo: Easy and effective file search
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emenegro
Hi houda.

Thank you so much for the quick response.

I attached a screenshot of the current map of the GMaps Location History. 

Captura de pantalla 2014-07-08 a la(s) 23.09.41.png 

As you can see there are a lot of points. This is a screenshot of the app with the photos geotagged.

Captura de pantalla 2014-07-08 a la(s) 23.14.05.png 

There are three main group of pins, and these are correct, but the photos are in wrong positions. For example, the last photo taken at 2:30am must be in the southwest group of pins, but it is located in the north one, when I got back to home 30 minutes after the pic was taken.

Is there an option in the app to see the date and time of each point of the track?

I expect this could help, sorry for my ignorance :(
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houdah
Hi,

No, HoudahGeo does not list individual track points or provide time info for these.

It does show start and end times of the tracks. Compare these to the times of the first and last photo and the times you think where track logs should start and end. Your HoudahGeo project is set to show GMT+2 times. I.e. the start and end times will be shown as GMT+2 times.

You can also inspect the track log using a text editor – like you did above. Here times are expressed in UTC. I.e. you need to "add" two hours when comparing to your photos.

HoudahGeo does not alter track log times: With your settings, it will display 15:19 UTC as 17:19 GMT+2. This is the exact same value / time.

If you have not changed settings on your camera since taking the photos, you can go to HoudahGeo camera setup and compare the current time shown on the camera with what HoudahGeo expects it to be. These times should be the same.

Best,
Pierre Bernard
Houdah Software s.à r.l.

Houdah Software s. à r. l.
https://www.houdah.com

HoudahGeo: One-stop photo geocoding
HoudahSpot: Advanced file search utility
Tembo: Easy and effective file search
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emenegro
Hi Pierre.

I will check again later today at home but there is a thing: when I export from the Location History (a couple of days in the same KML) it returns three days. For example, I'm exporting 5th and 6th of July but it returns values for the 4th, 5th and 6th, with these values as the first and the last

    <when>2014-07-04T15:04:45.668-07:00</when>
    <gx:coord>-3.6780849 40.4369476 0</gx:coord>

    <when>2014-07-06T14:59:23.296-07:00</when>
    <gx:coord>-3.6780812 40.4369898 0</gx:coord>

These dates and times, and correct me if I'm wrong, will be converted to GMT+2 so the 2014-07-04 15:04 of the first value will be 2014-07-05 00:04, and the same calculation for the last one: 2014-07-06 14:59 will be 2014-07-06 23:59, so the time ranges will be correct, 5th and 6th.

But, when I convert the KML to GPX using the GPSVisualizer I'm getting this for the first and last value

<trkpt lat="40.4369476" lon="-3.6780849">
<ele>0.0</ele>
<time>2014-07-04T15:04:45Z</time>
</trkpt>

<trkpt lat="40.4369898" lon="-3.6780812">
<ele>0.0</ele>
<time>2014-07-06T14:59:23Z</time>
</trkpt>

It seems to ignore the timezone -7:00 and assumes UTC, so tThese dates, converted to GMT+2 will not be correct, the first will be
2014-07-04 17:04 and 2014-07-06 16:59, clearly wrong. When I add this GPX to the app it shows me the first date at 4th and the last at 6th.

The problem is there, isn't it?

Thank you.

EDIT: in this page of GPSVisualizer I see a time offset options inside the advanced section, that could be the key...
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houdah
Looks like you found the problem.

Best,
Pierre Bernard
Houdah Software s.à r.l.
Houdah Software s. à r. l.
https://www.houdah.com

HoudahGeo: One-stop photo geocoding
HoudahSpot: Advanced file search utility
Tembo: Easy and effective file search
0 0
emenegro
Yes, it worked, that was the problem :D Thank you.
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