Guide to Advanced Geocoding Settings
Status: Beta
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===Camera time offset===
Your camera's clock is unlikely to be exactly set to the correct time. It's probably a few seconds off, and this will make the geocoding process less accurate.
Examples:
Your camera's clock says it's 2:00:05 when the real time is 2:00:00. Set the offset to -00:00:05 (subtract five seconds)
Your camera's clock says it's 3:09:00 when the real time is 3:10:00. Set the offset to +00:01:00 (add one minute)
===Thresholds===
Tracks are irrelevant when it comes to geocoding. All the points are treated as one big collection. You can control how (and whether) photos get geocoded by changing the thresholds.
Interpolation means that a photo is taken between two points, and the photo's location is guessed as being somewhere in between the locations of the two points. For example, two points are recorded - one at 12:00:00 and the other at 12:00:10 (10 seconds gap), and the distance between the two points is 10m. A photo is taken at 12:00:02, which means it was taken at 20% of the distance between the two points. 20% of 10m is 2m, so the photo's location is set to 2m along the line between the two points.
The longer the length of time that elapses between the point being recorded and the photo being taken, the less accurate the interpolation becomes. For this reason, you can set a threshold to control the maximum amount of time between a photo and the closest point for it to be geocoded using interpolation. If a photo was taken at 12:00:00 and the closest point is 12:05:00, with an interpolation threshold of 60 seconds, the photo won't be geocoded using interpolation.
The idea of the plan B threshold is that, say you take some photos at home, but you forget to turn on the GPS. You remember to turn it on 20 minutes later. If the plan B threshold is greater than 20 minutes, the photos will be geocoded using the location of the closest point (ie. not using interpolation).
Another example is, say you go for a day trip to another town. You forget to turn on the GPS for the first couple of hours while you are taking photos, then you remember to turn it on. You can set the plan B threshold to 120 or 180 minutes, and the photos will be geocoded using the closest point. At least you can get the general location of the photos, which is better than nothing.
===Reverse Geocoding===
Reverse geocoding means obtaining a location's name or address based on the latitude/longitude. DG Manager.NET performs this using Google Maps and GeoNames.org. If you are in a location covered by Google Maps, and near a street, the name of the street, suburb/town/city, province/state and country can be obtained. Otherwise GeoNames.org will be used, retrieving everything apart from the street name.
This data is inserted into IPTC metadata tags, such as the LocationName, CountryName, ProvinceState, CountryCode etc tags.
You can also optionally insert the address text (eg. "Chapel St, Prahran, VIC 3181, Australia") into various comment and keyword tags. The only tag that supports unicode characters is the user comment tag.
When you upload images to flickr (and maybe other online photo services) it will automatically set the description and tags based on the address information.
Reverse geocoding is simply wonderful. Thanks, indeed!
I wonder if it would be possible to use this nice feature also for photos that are already geotagged (e.g. manually). Just to load them into DGManager, without loading any point data, and reverse geocode them there?
Thanks again,
Cheers,
Martin
martin.senger@gmail.com
Yeah, it shouldn't be too hard to add this feature.
Consider these scenarios:
The interpolation threshold is set to 60 seconds and the plan B threshold is disabled.
- A photo taken 50 seconds from the nearest point will be geocoded using interpolation
- A photo taken 70 seconds from the nearest point will not be geocoded at all
- A photo taken 21 minutes from the nearest point will not be geocoded at all
The interpolation threshold is set to 60 seconds and the plan B threshold is set to 20 minutes.
- A photo taken 50 seconds from the nearest point will be geocoded using interpolation
- A photo taken 70 seconds from the nearest point will be geocoded, with its location set to that of the nearest point
- A photo taken 21 minutes from the nearest point will not be geocoded at all
===Misc===
"Set the modified date/time of the image file to the date/time used for geocoding"
If this option is enabled, the modified date of geocoded jpeg files will be set to the value of the "original datetime" EXIF tag contained in the jpeg plus or minus the offset (ie. this is the date/time that is used to determine the photo's location during the geocoding process). By modified date, I mean the date that appears in the "date modified" column in the details view of Windows Explorer, or in the file properties dialog.
If this option is disabled, the modified date of geocoded jpeg files will not be changed.
Hello, nice site :)
Hello,
I would really like to thank you for all your work that you share with us. I tried the last version and the improvements are just perfect and works very well for me. I live in France and I had the problem with the unicode characters but now there's no problem anymore.
Your software plus a flickr account is the perfect combination for me and the reverse geocoding feature really saved me a precious amount of time.
So thank you for your great software and the nice guide you wrote (he will help me to improve my geocoding skills;)
Have a nice day,
Best regards
Montafor
Thanks, I'm glad it's working for you now.