Thursday, October 2, 2008

Testing the GPS in the Nikon Coolpix P6000. Verdict: Good enough

Nikon P6000About 24 hours ago, I finally received my Nikon Coolpix P6000, the first quality Nikon compact (i.e. "point and shoot") camera with built-in GPS. I was quite eager to test this camera, for reasons obviously related to Nelso's goal of collecting business data for most of the world's major cities. Over these 24 hours, I've used the in-camera GPS under a variety of conditions, and can report that the quality of the GPS, while not up to the standard of a high-end handheld unit like the Garmin 60CSx, is still very good, and more than satisfactory for most uses.

This is just a test of the GPS inside the camera. If you want a full review of picture quality, RAW file formats, lens focal lengths, etc. it's best to wait until a site like dpreview.com or kenrockwell.com do a full write-up. Currently the camera is so new (even Flickr isn't tracking the P6000 yet) that no full-length reviews are available.

I'll jump right into the accuracy testing, and then will finish up with a few general comments about the GPS hardware.

Accuracy Tests

In all of the examples below, the marker labeled "A" marks the spot where the Nikon P6000 GPS thought I was standing or driving (more on shooting from a car below), and the marker labeled "B" indicates the correct position.

Shooting from a position where you have a clear view of the sky

Below are photos I shot with the camera once I'd turned on the GPS and allowed it to get a strong signal from six satellites. Under these conditions, the error is approximately 3-10 meters (9-30 feet).



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Shooting from a moving car

I was curious to see how the Nikon P6000 would perform when shooting from inside a moving car, where the GPS would have a limited view of the sky (I was in a minivan, not a convertible), but would still be able to track a few satellites through the windows. Despite having been in the car for more than 10 minutes (and thus not having a clear view of the sky for that time), the GPS performed remarkably well. The error was between 30 and 100 meters (90-300 feet) under these conditions.


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Taking a photo after having just left a building

What happens when the camera has no view of the sky for a few minutes, and then is taken outside again? In this case, I left the camera inside for about 10 minutes, then went back outside. I let the camera get an initial track on a few satellites, but didn't give it the time it would need to track 4+ satellites and thus get a more accurate reading. This seems to me a reasonable test case, as many users will go inside a building for a while, and then come out and start shooting very soon after having a view of the sky.


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Performance was not bad (about 36 meters/110 feet off). In this case, it would have been more accurate to not have let the camera get a fix on my location at all, and have it fall back on its last recorded position (right before I entered the building on the right of the map above).

Shooting inside a building (i.e. no ability to track GPS at all)

In this case, I took a photo after having been inside a shopping mall in Prague for more than half an hour. Thus, there was no chance that the GPS in the camera could get a reading. What the camera did do was use the last valid GPS position that it had recorded before it lost satellite reception, placing me at the entrance to the mall itself. This seems to me a very satisfactory solution (more on this below).

Sam checking out Harley Motorcycles at Metropole Zlicin


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Other comments on the GPS in the Nikon P6000

It's very slow to get an initial position

When I took the camera out of the box and turned on the GPS, I actually thought the GPS in the camera might be broken. Even standing in the middle of a parking lot with a clear view of the sky, it took over 10 minutes for the camera to detect even the first satellite. While it's not unusual for a new GPS unit to take a while to get an initial fix on its position (the GPS has no idea even approximately of where it is; for all it knows, it might still be at the factory in Vietnam), an initial startup time of more than 10 minutes is excessive, and might lead other purchasers to believe as I did that the GPS is actually broken.

What's more disappointing is that the time to fix an initial position, after the camera has been off for a few hours, can still be 3-5 minutes depending on your view of the sky. I think some users will not pay enough attention to the GPS and will start shooting before the GPS has a chance to fix a position, leading to photos with no embedded GPS data.

Once you do get an initial fix on position, the camera updates its position data every 5 seconds, and this works well. If you switch to "GPS" mode on the camera (the display will then show a live update of your GPS coordinates as you move) it's clear that it tracks well. It's just that it'd be nice if, after leaving a building or turning on the unit in the morning, it wasn't necessary to stand out in a clear area for five minutes holding the camera up in the air before taking the first picture.

No "accuracy" info on the GPS display

Although the camera will show the location of satellites that it is tracking and your current coordinates on the display when in "GPS" mode, it is missing the all-important "accuracy" number. A dedicated Garmin GPS unit will not only show how many satellites it can see, but also an estimate of the accuracy of the coordinates that it is reporting. This is very useful when trying to determine if you are standing too close to a building, or under too much tree cover to get a good reading. The Nikon P6000 simply uses a three-segment display to show accuracy, and the third (best) segment seems to light up whenever accuracy is better than about 50 meters / 150 feet. This is not good enough. Hopefully a firmware update can add accuracy numbers to the GPS display, or at least add another few steps to the accuracy scale.

Writing GPS data to EXIF headers with no view of the sky

When you go inside a building, or any other area where GPS can not be used, the camera will use its last position to tag photos with location data. You can set the "time to live" of this GPS position data, which is very useful. How it works is this: you tell the camera the maximum age of the last point to use when tagging photos when it can't get a current fix on position. You can set this to anywhere from 15 seconds to two hours. Thus, if you have a "maximum validity" of one minute for GPS data, and you take a photo 30 seconds after losing contact with the satellites, you will get GPS data in the photo, but if you take a photo 90 seconds after losing contact with the satellites, you will not get GPS data in the photo.

Assuming that a user sets this to something useful like 1-2 hours, this will be a great feature for tourists. You won't be able to track yourself as you move around the Louvre in Paris, but at least all your photos from your tour of that museum will be tagged with a location at the entrance to the building. Good enough.

You can set the date and time on your camera using GPS

You can set the time and date on your camera (but not the time zone) using the built-in GPS. This seems like an obvious thing for the software to support (of course, you never know; the iPhone still doesn't support cut-and-paste), but I'm still glad they included this feature. My experience with other Nikon cameras like the D40 is that the on-board clock is quite inaccurate.

What's the GPS chipset in this thing?

None of the spec sheets that I've come across were able to tell me what GPS chipset is used inside the P6000. Knowing this would have given me a better idea of what to expect in terms of accuracy. I guess we'll have to wait until someone takes one apart to find out.

Summary

I must say that I am quite pleased with the P6000, and that the accuracy of the GPS is easily good enough to make it useful. For most consumers, even accuracy of 100-200 meters will make looking through travel photos much more enjoyable (no more "Where was this shot?"). For our use, it will also work, assuming we take a few precautions to make sure we always get the best possible accuracy from the camera.

However, if you want really accurate GPS data, especially in more demanding situations (very close to tall buildings, under extensive tree cover, inside a moving vehicle, etc.), the best route is still a camera paired with a dedicated GPS unit, either tethered directly to the camera, or recording your track to be synchronized with the photos later using an application like GPSPhotoLinker.

14 comments:

MidNight Mapper said...

Just a comment on your disappointment regarding out-of-the-box initial turn-on to first sat lock.
All GPS units require two reference tables to be current and if not they must updated by undisrupted listening to “a” for a period of time. The larger table the almanac requires upwards of 10 minutes of uninterrupted lock on a satellite. And the ephermic table needs a minute or three before satellite lock can be achieved. The almanac is essentially the bus schedule that provides the essential “coarse” schedule for all satellites. Generally it must be no older than a week or three and if older it must be updated. Absence or presence of a stale almanac requires the update of its table which requires around 10 minutes and “constant lock to at least one satellite” to be fully loaded at the bit rates. Break the lock and it must reacquire and initiate refreshing of the almanac all over. So if you store your unit for more than a couple of weeks – expect 10 or more minutes minimally to regain a proper table.
You point on moving your GPS several hundred miles from its last known position when almanac and ephermic are current can also confuse your unit. This lag is a result of GPS unit believing it is in the same area when it was turned off. It looks into the almanac, its clock, and then hunts for the predicted satellites based on its last known position. If it can not find those most likely satellites it falls into a search and find solution… for at least two or more satellites; this too delays the locked navigation. Giving the unit a hint can speed this up significantly… geo-smartphones use the local area code for the hint.
The last step to getting the best solution is the updating of the ephermic table. This is the very fine resolution on the coarse almanac and accounts for things like tidal effects, day/night, and other fine tunings on the satellites’ paths. This information can be updated several times in an hour. The ephermic table is also the reason why cold starts with current almanacs can require upwards of a minute or more to properly lock and for accuracy to stabilize. This is where the a-GPS advantage can be found in certain geo-smartphones to improve time to navigating lock. These phones will hunt the ephermic table first from the carrier gaining this update via the mobile web feature… also allows the carrier to keep you locked to them as well?
MidNioght Mapper

Anonymous said...

Thanks for posting your tests, I have been thinking about purchasing a P6000 but wanted to know a little about well the GPS works first.

I have a question reguarding the accuracy of the GPS in the camera.

What method was used to mark the "B" or correct position in your test?

Were you using another GPS, or were you visually placing the markers baised on the Google Sat Imagery?

I have been tagging photos for some time with a Coolpix P3,Garmin 60C, and RoboGeo software.

I have come to the conclusion that my GPS is much more accurate that the Google Maps of my area.

It is common for me to take a photo of a building, with my GPS showing an error of 8 feet or less, but when I plot the location on Google Maps, I am as much as 50 to 80 feet away from the matching location.

Would it be possible for you to do take a few photos of you Garmin Csx with the P6000 to see how closely they compare?
Thanks,

Jeff

Anonymous said...

Some questions to which it seems the internet doesn't have any answers yet:

- is it possible to upload to anywhere else than nikon's mypicturetown? Maybe using ftp, http post/put, webdav or anything else?

- does the camera have any open tcp/udp ports when connected to the lan? I mean, could it be possible to "log in" to the camera and download the images?

thanks!
ben

Jack DeNeut said...

Jeff - The "B" location was just done by me by hand, assuming that the Google Maps are correct. Based on my experience with my Garmin, I think the Google Maps data is pretty good.

I'll try to take a picture of my Garmin 60CSx and the Nikon P6000 side by side and post it here on the blog.

Criss.AC said...

I've seen a location on a map from your article, Zlicin. If I'm not mistaken, that's in Prague, isn't it? Anyway. I have got your page google-ing about GPS and Nikon CoolPix P6000, which is also my new camera as well, for less than 24h. And yes, by reading your article about how GPS performs on it, I do think I have made a good choice. Also, looking forward to a firmware update. All best!

PS: I see that you had(ve) a D40. Do you know if there's any authorised Nikon shop in Prague where from we could get accessories for our cameras?

Jack DeNeut said...

criss.ac - I think the best camera shop in Prague is Centrum Foto҆koda. They have lots of lenses and other accessories for Nikon cameras.

And yes, Zlicin is in Prague (I live in Prague 6). I'm looking forward to them opening a Burger King in Prague there.

Anonymous said...

I'd be careful placing pictures visually on google earth, some places are off by a few meters. Best way to know is if several all consistently 4 meters to the left (like where I live).

GPS accessories said...

I have enjoyed reading.Nice blog.

Fredrik said...

Hi!

I really like your post, what you don't consider though is the battery life.

How is the battery performance effected when using the GPS? Is there any smart (or perhaps simple) way to save battery but still make use of some GPS functionality? The reson I'm asking is that I'm planning a trekking trip and need a new camera for this trip. I'm proabably going to take a lot of photos and would also have some use of the GPS. How many bateries should i bring for a five days hike?

Jack DeNeut said...

Fredrik - the battery life on the P6000 is not great, but this is to be expected in a compact camera with a small battery and an on-board GPS. I'd bring at least one battery for every day of your trip. I have many batteries for my P6000 cameras (and the P5000, which has the same battery). There is no need to buy the Nikon EN-EL5 battery, as you can get compatible batteries from other manufacturers for much less. I've tried many of them and they work fine.

The most important thing to do to extend the battery life on your Nikon P6000 is to make sure the GPS is completely off when you are not using the camera. Once you turn GPS on in the settings menu, even when the camera appears to be "off", the camera will still leave the GPS on and try to keep track of where it is. It does this to reduce the time required to get a GPS fix once you turn on the camera. However, this means that the camera will be using up the battery all the time, not just when you are taking pictures.

You can go in to the settings menu and turn the GPS off when you are not using the camera, but this is kind of a hassle, and also increases the chance that you'll forget to turn the GPS back on when you take pictures, and you'll get home and find out you don't have GPS data for some or all of your photos.

It's much easier to just take out the battery if you'll not be using the camera, especially at night. No reason the camera should use up the battery trying to find its position all night while you are sleeping and not taking pictures.

Anonymous said...

Do you have any update on how well the Nikon Coolpix P6000 performs now that you have had it several months? I am very interested in an integral gps camera so I won't have to post process my photos and tracklog. Have you ever used it under forest cover? How did it do?
Thanks,

Anonymous said...

Compared the P6000 to Ricoh's newest GPSed camera solution. I found the 500SE to be a much better GPS solution. The geotag on the 500SE has far more data collected compared to the P6000. The Nikon doesn't log the list of satellites used which is a bit lame but the really bad news is that it fails to collect Dilution of Precision info which is the stat that should be used to determine the reliability of the GPS data collected. Granted the 500SE is considerably more expensive but satellites and PDOP should be logged by the Nikon. The other disappointment with the P6000 is that there appears to be no way to direct upload of the photos to anywhere other than Picturetown. That hard connected Ethernet cable would be a great way to collect photos from field staff into a common Enterprise IT media storage area if one could push the pics to a specific WWW site the user could set via firmware of the camera. I also have had trouble getting the P6000 to lock on. I flew from Annapolis to New Orleans and it took several attempts and a few hours to finally get a geotagged photo.

Cara said...

I had no idea they even put GPS units in cameras; I'll definitely be looking into getting one. Currently, the GPS I have in my car is the amazing Garmin nuvi 2360LT, which is absolutely the best unit I've ever had. So before I snag a camera with GPS, I'll definitely want to see how it's specs compare to the Garmin I already have on hand - otherwise I might just carry that one around with my camera!

Criss.AC said...

@Cara: you're making a confusion. The GPS in the camera is not a navigator, unlike the GPS units you'll find in a car. The purpose of the GPS in the camera is to geo-tag the pictures, so after you download them on your computer they'll show the location where you've taken them.