Accuracy of GPS position in EXIF is lower than it could be

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22

Accuracy of GPS position in EXIF is lower than it could be

asked 2014-04-13 14:06:44 +0200

Mikecc
221 ●2 ●4 ●5

updated 2015-04-27 01:36:37 +0200

Self-Perfection

2496 ●37 ●53 ●49

have installed 1.0.5.16

I'm happy now that positions are stored in the EXIF of the pictures. BUT: Format is DD MM SS (degrees/ minutes/ seconds) and seconds are truncated. Please donate 2 more digits after the seconds dot. Same story was on N900 https://bugs.maemo.org/show_bug.cgi?id=11934 See attached photo from yesterday: exif says:

Nördlicher oder südl|N
Breitengrad         |49,  0, 15
Östliche oder westli|E
Längengrad          | 8, 46, 29

is latitude/longitude -> should be something like 49, 0, 15.12 resp. 8, 46, 29.34

.12 and .34 are just examples...

Additionally it would be great if some more properties (like coordinates, compass direction and altitude) would be displayed Pictures properties, if GPS tagged photos would be marked with a small icon in gallery and if I could send the position to a map application (like "Here" :-) to see were the photo was taken.

But on the first approach the accuracy is really urgent for me to use the phone for OSM mapping.

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Two decimal places would only enable an accuracy of at the most 30cm, why not 3 or 4 decimal places to ensure that we are certain to be inside the minimal error of the A-GPS/GLONASS system, even with future software updates?

00prometheus ( 2014-04-13 16:24:07 +0200 )edit

1

Yes, sometimes I'm overmodest :-)

2 decimals would at least today sufficient for my interests. What I forgot: Very helpful would be the direction. The Java OpenStreetMap Editor can visualize it. After a longer mapping tour I see where I took the photo, but not in which direction I took it. Sometimes sun/shadow helps, sometime not...

A "nice to have" would be the altitude, but is not so important compared to better position accuracy or altitude info.

Mikecc ( 2014-04-13 19:12:25 +0200 )edit

I agree with you, why using human readable format with fixed digits instead of a plain real value.

Besides, the field Xmp.exif.GPSLatitude has indeed already more digits if you need them before a possible fix from Jolla for the exif tag itself.

Damien Caliste ( 2014-04-24 17:22:25 +0200 )edit

1

In practice the accuracy of gps in mobile phones dont have this accuracy. If it diwn ti a few meters we should be very happy....

polarphone ( 2015-10-02 15:29:21 +0200 )edit

Two decimal places would only enable an accuracy of at the most 30cm, why not 3 or 4 decimal places to ensure that we are certain to be inside the minimal error of the A-GPS/GLONASS system, even with future software updates?
00prometheus ( 2014-04-13 16:24:07 +0200 )edit
Yes, sometimes I'm overmodest :-)
2 decimals would at least today sufficient for my interests. What I forgot: Very helpful would be the direction. The Java OpenStreetMap Editor can visualize it. After a longer mapping tour I see where I took the photo, but not in which direction I took it. Sometimes sun/shadow helps, sometime not...
A "nice to have" would be the altitude, but is not so important compared to better position accuracy or altitude info.
Mikecc ( 2014-04-13 19:12:25 +0200 )edit
I agree with you, why using human readable format with fixed digits instead of a plain real value.
Besides, the field Xmp.exif.GPSLatitude has indeed already more digits if you need them before a possible fix from Jolla for the exif tag itself.
Damien Caliste ( 2014-04-24 17:22:25 +0200 )edit
In practice the accuracy of gps in mobile phones dont have this accuracy. If it diwn ti a few meters we should be very happy....
polarphone ( 2015-10-02 15:29:21 +0200 )edit

Answer 1

9

answered 2015-04-28 01:16:46 +0200

Self-Perfection

2496 ●37 ●53 ●49

Hey, I've run into this problem during OSM mapping party when I was trying to process photos from the streets to submit features to OSM database.

However during close examination of photos I've noticed that XMP tags has coords with enough precision

$ exiftool -a '-exif:GPS*itude' '-xmp:GPS*itude' "$FILE"
GPS Latitude                    : 55 deg 44' 27.00"
GPS Longitude                   : 37 deg 39' 18.00"
GPS Altitude                    : 170 m
GPS Latitude                    : 55 deg 44' 27.25" N
GPS Longitude                   : 37 deg 39' 18.09" E
GPS Altitude                    : 170 m

Unfortunately tools prefer reading GPS data from EXIF tags and therefore uses rounded coordinates. Here is workaround to restore precision of EXIF GPS tags from XMP tags for single file:

exiftool -tagsfromfile "$FILE" '-xmp:GPSLatitude>exif:GPSLatitude' '-xmp:GPSLongitude>exif:GPSLongitude' "$FILE"

For all files with .jpg extension in current directory:

exiftool -tagsfromfile ./%f.%e '-xmp:GPSLatitude>exif:GPSLatitude' '-xmp:GPSLongitude>exif:GPSLongitude' -ext jpg .

You may add -overwrite_original_in_place CLI switch if you are a brave one or have external backup.

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Answer 2

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answered 2015-10-02 15:12:51 +0200

cemoi71

14264 ●310 ●434 ●439

Hi TJC

i am really interested on this feature.
I would like to suggest for it a special feature:
The photo app should give a feeling what should be activated so that it is possible to use agps in good conditions.
Currently it is not obvious for all.
For example: Gives some visual feedback that gps is on, accuracy through network (wifi or mobile-net) available or not.
And give catched position...

Nice time to all

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Accuracy of GPS position in EXIF is lower than it could be

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