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bonzon

When reading a NMEA log, HoudahGeo will extract the track direction and save it into the GPSImgDirection EXIF tag during export. This is wrong, it should be saved into GPSTrack.

From EXIF reference:
GPSTrack: tells the direction of GPS receiver movement.
GPSImgDirection: tells the direction of the image when it was captured, i.e. the angle of the direction that the camera points to.

These two fields are equal only when the camera is aligned with direction of travel, i.e. facing the front in the direction of travel.

Say you are in a car taking a photo through a side window, then the GPSImgDirection has 90° difference with GPSTrack. Or, if you are taking photos towards the back (with respect to direction of travel), the GPSImgDirection is 180° off the GPSTrack.

Some cameras have integrated compass (typically smartphones) and will record a true GPSImgDirection. A GPS log like NMEA can't infer anything about GPSImgDirection, but only about GPSTrack.

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houdah
Hi!

The image direction saved by HoudahGeo is the combination of the direction of travel and the offset you entered. The direction of travel is taken from the GPS track where available.

If you have been taking photos out the side window, you can select multiple images in HoudahGeo and set the view offset for all of these to 90 degrees.

HoudahGeo does not currently store a value for GPSTrack.

Best,

Pierre Bernard
Houdah Software s.à r.l.

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

HoudahGeo: One-stop photo geocoding
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bonzon
Thank you, it makes sense now. HoudahGeo Direction is always meant GPSImgDirection. The documentation does not make this clear.

The Direction Offset column is used to convert GPSTrack to GPSImgDirection with a manual input, for cases where the image capture direction is not facing the direction of travel.
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bonzon
I'm trying to use this Direction Offset column, but it does not work as expected.

I can reproduce this bug with HoudahGeo 4.1, Mac OS X 10.10.3:
- Load sample image below in HoudahGeo
- Set any coordinate
- Set Direction 123°
- Set Direction Offset 90°
- EXIF/XMP Export on original

Actual:
- GPSImgDirectionRef tag created with True North
- No GPSImgDirection tag created

Expected:
- GPSImgDirectionRef tag created with True North
- GPSImgDirection tag created with 213

A GPSImgDirection tag is created though for low values, e.g. Direction 10°, Direction Offset 20°. After some trials, it seems the maximum Direction + Direction Offset that HoudahGeo is willing to write is 36°. Happens to be tenth of 360°. Coincidence?


sample.jpg 
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houdah
Hi!

Thank you for reporting this bug.
I will release a fix soon.

It was not a coincidence. It is indeed the code making sure that the value is no greater than 360 that was broken.


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!

I have a new beta of HoudahGeo:
https://dl.dropboxusercontent.com/u/2381634/HoudahGeo/HoudahGeo4.1.3b3.zip

This version adds support for GPSTrack and GPSTrackRef.
It writes direction GPSTrack. It writes the sum of direction and offset to GPSImgDirection.

Please give this a try and let me know how that works for you.

While this feature is being tested in a beta of HoudahGeo 4.1.3, it may not be released with that version. It may have to wait for a later release.

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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bonzon
Cool. It works as expected.

Minor issues:

- Can you get rid of the rounding artifacts? (Problem already present in 4.1.2) E.g.:
Direction: 243.60
Offset: 270.00
Actual GPS Img Direction: 153.6000061
Expected GPS Img Direction: 153.6

- When filling in any Speed value for a single photo, either in the Inspector right column or in the Images list, it will always validate to "0.00 km/h" instead the number I typed. (Problem already present in 4.1.2)

- Increase "EXIF/XMP Export" dialog window height to accommodate for the new line.

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houdah
Hi!

Thank you for reporting these issues.
These will be fixed in the next update.

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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bonzon

I confirm version 4.2 fixed all above issues.

I see a new minor problem. The same rounding problem that was happening for Direction happens for Speed:

Typed in HoudahGeo: 12.34 km/h
Actual in EXIF: 12.3400008
Expected in EXIF: 12.34

Typed in HoudahGeo: 56.78 km/h
Actual in EXIF: 56.77999203
Expected in EXIF: 56.78

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bonzon
Speed rounding fixed in version 4.2.1. Thanks.
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