Detailed camera time adjustment

Sirius

1

« on: 15 / January / 2011, 23:46:22 »

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Hey guys,

First post, but I've been using CHDK for 3+ years on my A610, and loving it! Just a big thank you to all the devs, testers, and community!

I just had an idea while geo-tagging my photos: Is it possible for CHDK to change the system clock of the camera down to the seconds? This will better facilitate syncing the camera time to GPS time.

The default time adjustment function of the camera only goes down to minutes, and a camera can change locations by a few km's in that minute (if you were on a car or train, for example), so accuracy down to seconds is crucial for geotagging to be useful. At the moment I'd have to manually sync the time by:

Taking a photo of my GPS tracker while I press the POI button on it
Uploading the photo and GPS track to my computer
Finding that POI point on the computer
Working out the time difference between that POI and the photo I took
Time-shifting all the photos in that batch to match the GPS time

Which is a tedious process, to say the least

I see that CHDK can see the system clock down to seconds, but can it change it? Perhaps even provide a way to reset the seconds to zero with one menu option (similar to the radio-time-sync function on many clocks in cars). This would make keeping the camera time synced to GPS time so much easier!

Slightly off topic, is there a website which displays actual real-time GPS time? The only ones I've found get the time from the user's own computer (which it takes to be UTC/GMT+timezone), then works out offsets unique to the GPS time system; if the user's computer's time is off, the GPS time is off too...

Thanks for your replies!

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reyalp

14003

Re: Detailed camera time adjustment

« Reply #1 on: 16 / January / 2011, 01:30:13 »

Quote from: Sirius on 15 / January / 2011, 23:46:22

I see that CHDK can see the system clock down to seconds, but can it change it? Perhaps even provide a way to reset the seconds to zero with one menu option (similar to the radio-time-sync function on many clocks in cars). This would make keeping the camera time synced to GPS time so much easier!

I don't think we currently have a function to set the clock. It could probably be found.

Quote

Slightly off topic, is there a website which displays actual real-time GPS time? The only ones I've found get the time from the user's own computer (which it takes to be UTC/GMT+timezone), then works out offsets unique to the GPS time system; if the user's computer's time is off, the GPS time is off too...

Not exactly what you are asking, but you can use NTP to synchronize your PC clock to an external source. With a reasonable network connection, NTP is capable of very good accuracy. Windows "Internet Time" is an NTP client, although AFAIK it defaults to only synchronizing once a day or something like that.

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Don't forget what the H stands for.

SkyWalker9

301
SX20 IS (fw 1.02b)

Re: Detailed camera time adjustment

« Reply #2 on: 16 / January / 2011, 11:59:12 »

Quote from: Sirius on 15 / January / 2011, 23:46:22

...Is it possible for CHDK to change the system clock of the camera down to the seconds? This will better facilitate syncing the camera time to GPS time...

Here is another process that you might want to consider - geo-synching photos to a GPS unit using two freeware apps: EasyGPS and GPicSync. I have been using this process for sometime. The only criteria is that your GPS unit needs to work with EasyGPS. I keep my camera on local time (with the minutes/seconds matched to GMT) and the GPS uses GMT time.

1. Upload GPS Waypoints/Routes/Tracks/Photos/Geocaches using the free PC app EasyGPS (freeware - http://www.easygps.com/ )
2. Save info as a GPX file
3. Load GPicSync (by Google - freeware - http://code.google.com/p/gpicsync/ ) and use that GPX file as the "GPS file". Select your "Picture folder".
4. Set the "Geocode picture only if time difference to the nearest track point is below (seconds)=" to allow for small differences in seconds (usually less than 180 seconds)
5. Select the "Options" tab and "Local Time Correction" where it will allow you to set the time of your camera and the time GPS unit time (both down to the seconds), Press "Apply Correction"
6. Select "Synchronise !" and GPicSync will align the photos to the GPS time and geocode the photo as it finds the matches.

Each photo is then compared to the GPS times and geotagged if it meets the criteria. If it can't find a GPS time that matches the photo time it will not geotag the photo but it wil indicate the closest time match and how much the time differs in seconds. The progress is shown in a scrolling window of the application that can be viewed later.

I also check the "backup pictures" option to save the original photos in a "Originals" folder in the same folder as the photos.

Quote

Slightly off topic, is there a website which displays actual real-time GPS time? The only ones I've found get the time from the user's own computer (which it takes to be UTC/GMT+timezone), then works out offsets unique to the GPS time system; if the user's computer's time is off, the GPS time is off too...

http://wwp.greenwichmeantime.com/

« Last Edit: 16 / January / 2011, 12:04:09 by SkyWalker9 »

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fudgey

1705
a570is

Re: Detailed camera time adjustment

« Reply #3 on: 16 / January / 2011, 12:06:09 »

Quote from: Sirius on 15 / January / 2011, 23:46:22

The default time adjustment function of the camera only goes down to minutes

Are you sure it doesn't clear seconds when you press ok, like many devices that ask time in HH:MM do? In that case you can set time accurately, you just need to wait up to 59 seconds to be able to do it. To automate, you could cook up a script that emulates keypresses and communicates via PTP to a PC.

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SkyWalker9

301
SX20 IS (fw 1.02b)

Re: Detailed camera time adjustment

« Reply #4 on: 16 / January / 2011, 20:05:02 »

Quote from: fudgey on 16 / January / 2011, 12:06:09

Quote from: Sirius on 15 / January / 2011, 23:46:22
The default time adjustment function of the camera only goes down to minutes
Are you sure it doesn't clear seconds when you press ok, like many devices that ask time in HH:MM do? In that case you can set time accurately, you just need to wait up to 59 seconds to be able to do it. To automate, you could cook up a script that emulates keypresses and communicates via PTP to a PC.

@fudgey is correct. For example, when setting the time on the SX20 you only enter the HH and MM - no seconds. You just have to be sure to set just as the minute changes.

Most cameras record the time saved in seconds, but it is saved in the photo EXIF data. When you look at the time stamp for the photo using Windows Explorer, it only shows the HH:MM, but if you do right button click on the photo and select properties you'll see that the seconds were also recorded by the camera.

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