- Location
- Hillbilly shack in the boonies
Interesting New GPS from Bushnell !
- Thread starter Levi Garrett
- Start date
- Location
- Hillbilly shack in the boonies
Ya Baby, give it 5 years till there is quality detail in most locations 
Demand will dictate progress.
Demand will dictate progress.
Last edited:
I use orthophotos and basemapping data all the time. My best guess is this isn't going to replace topo maps anytime soon.7mm-08 said:
I haven't seen any of these products yet, and they definitely have intriguing possibilities, but there are a couple of issues out there.
First, what satellite imagery are they using? Ikonos or Quickbird? Doubtful. Probably Landsat. At it's very best, Landsat will give you.... ummmm... 15m per pixel, I think with pan sharpening. And due to the manner in which pixels are sampled, those pixels aren't always truly representative - because the pixel has to choose one color/greyscale value to represent everything within that square pixel. So, for example, if you have a very small, shiny object within that 15m square pixel, it will overwhelm what does make up the vast majority of what does occupy that area and represent it as though it were all shiny.
Second, handheld GPS screens are still reasonably small, pixel wise. So there are some issues with how to display these satellite photos in useable format on very small screens with relatively low resolutions. Bigger screens with bigger resolutions equals greater power demands equals more/bigger batteries... Remember, best case with these units are 320x240 pixels.
Third, these aren't going to be live satellite feeds, so you have to wonder how old the satellite photos are going to be. They'll be looking for satellite photos with 0% cloud cover, and those can be hard to find. Landsat goes back at least several decades; we regularly look for 0% cloud cover images to do land change comparisons between two different years, and finding useful imagery can be difficult. Aerial photos should be better, but basically more of the same.
On a personal note, we already have the capability to import orthophotos and orthorectified satellite imagery into professional GPS units with much higher resolution screens and running Windows CE. I originally did that on a few projects and then concluded it was mostly worthless to doing the job and not worth the trouble. I've gotten into the habit of simply loading the NRCAN topo maps (orthorectified of course) into the GPS, along with clipped basemapping for the area selected from the TRIMII datasets. Much of the time, I don't even bother doing that.
Fundamentally, I'm sure it'll still be a very useful GPS, but I'm not sure many will actually find the ability to import satellite data truly useful - I'll bet it'll help "accessory" sales for Bushnell, however!
BC Bigbore
CGN frequent flyer
- Location
- BC's Peace Country
Ditto. Geekology was never my strong point
- Location
- Hillbilly shack in the boonies
Would be better , no leaves on the trees, trails show up nice , And easier to see hardwood versus softwood for pockets of bedding area etc.Lazy Ike said:
Well, you'll find the same language used in Ozie Explorer which is a popular amateur mapping software.huntinstuff said:
The map service being offered by Bushnell is orthorectified aerial photos and satellite images for your GPS. They aren't of much use if they aren't spatially aware - i.e., they know exactly where to appear. "Orthorectified" means the image has some information encoded into it that tells it exactly where to appear in a GPS or other spatially aware device or software. An aerial photo of the Elk Valley isn't much use if it decides to appear in your GPS somewhere in New Jersey instead of in the proper place in BC. If you are going looking for them online to download them, therefore, you are looking for "orthophotos" or something similar. You don't need to do the orthorectification process - people like me do it for you and provide the finished product.
Landsat, Ikonos, and Quickbird are probably the most common satellites used for satellite imagery. Google them; you'll see some cool pics...
Resolution is just like your computer monitor. The finer the pixel size in the image, the more detail the satellite can show in an image. The pixel can only be one color, so the sensor has to evaluate all the colors in the boundary that pixel is "looking at" on Earth, and decide to choose which color best represents that. So for example, you have a Landsat "photo". Each pixel is a 15m square. I can think of more than a few places where a whole bunch of 15m square pixels could all have a logging road, part of a lake, evergreens, and decidious trees in fall colors all in that one square. So... which color should each pixel be?
If we get a better image, of course - say each pixel being 60cm square, then we're going to get sharper and more "photo accurate" pictures, right - how many 60cm pixels can you fit in a 15m square box? BUT... more pixels equals more memory requirements to store that image. No different than comparing a picture taken with a 2 Mb digital camera versus a 10 Mb digital camera.
Zoom in on the pictures taken by Landsat versus those taken by Quickbird, and you will immediately understand the difference if this is a bit confusing. From memory, Landsat's best resolution is 15m, Ikonos is 1m, and Quickbird is 60cm. Also from memory, the image can only properly resolve objects that the minimum pixel size is 3/4 the size of. So Quickbird can resolve objects (to the point they can be clearly identified) of a little less than a meter - you could see an elk. Landsat has no guarantees of resolving anything with a dimension smaller than 20 meters - meaning it won't show creeks, roads, etc unless they are very bright and overwhelm every other "color" in that particular pixel.
Bottom line, very little satellite imagery is suitable for use in the way most people think of it as, a "picture". It is more often used to map differences over large area - the amount and border of pine beetle kill in a forest, for example. In fact, more often than not, it doesn't even look like a picture - the satellite can pick up electromagnetic radiation (which visible light is part of) in the ultraviolent, infra-red, near infra-red, far infrared, etc wavelengths. So more often than not we are using bandwidths in satellite imagery that aren't even visible to the human eye. Thermal imagery like the NODLR we have in the Canadian Forces is an example of using that on the ground.
Again, maybe the best thing to do is google the satellite names and look at the example imagery to get a sense of what the results can look like. Actually, here's a couple of links: the first is Quickbird (which is as good as it gets), the second is Landsat, the most common imagery out there. Both of are forest fires, so you can get an idea of what bush roads and features would look like:
http://www.digitalglobe.com/images/qb/grandprix_ca_october27_2003_dg.jpg
http://landsat.gsfc.nasa.gov/images/lg_jpg/e0007_10.26.06.jpg
The last part of the equation is, remember, your screen is something like 240 pixels wide on this GPS at the most. So, if you were using Quickbird photos, you could view 240 pixels x .60 cm at a time. So you'll be able to see detail of around 144 meters at a time - a pretty focused view.
Aerial photos are often much clearer but only magnify the problem with a small viewing area and dense data. To give you an example; here's an aerial photo with 15cm resolution - you can see cows, rail ties, etc.
The image is 800 pixels wide - so you could only see about one third of it on your GPS screen at any one time. Take a look at that image - a not uncommon scene within the areas we hunt in - and then ask yourself how useful that would be.
Anyways, satellite imagery and aerial photos can be very useful and it isn't that hard to learn all about them - Google is your friend. They can certainly be used for scouting from home, identifying areas to give a closer look, printing out on large map-size sheets, etc.
But at this point, I think they're more about the LCF factor than anything else, as far as handheld GPS's go. Something like a Garmin with the digitized Canadian NRCAN 1:50,000 maps is something that's truly useful, and I use it all the time, even in professional applications.
