Remember that you GPS signal is going to be affected by many things other than the internal electronics. Things like over-story, cloud cover, position of the satelites will all influence the data. This is why when people are doing stuff that requires solid datasets, they will place down the GPS and let it record a series of points without moving it. Then, you put the points into the GIS and you are able to get an idea of the precision. It is also possible for you to geocorrect the coordinates.
I suggest that if you are seriously concerned about accuracy of less than a meter that you use a model comparable to a Trimble XM or higher. If your accuracy can be within a hundred feet, its less serious. I am not sure how good garmins are these days, but all the GPS units are increasingly better than only five years ago. One option you could use is to take the GPS camera and take maybe a dozen pictures of the exact same waypoint. Do this at each of your study sites. More pictures would be better. Then, you take the coordinates for each picture at each site, and average them. This will give you a mean with SD or SE. This way, you will know the actual accuracy and precision of the unit under the weather conditions at the site where you were collecting data. You can also check this against a better GPS unit if desiered. By doing this at one point, then moving about your site, you will know the error and can report some kind of confidence in regard to the location of each point where vegetation is photographed. It will probably have pretty consistent precision on any given day within a specific site. This is a fair assumption, but some testing at home or on campus should be conducted to verify it. one thing to also remember is that what is reported in the paperwork is best case scenario. The model will almost never reach this precision/accuracy in teh field. The high-dollar GPS units will be more consistently close than the cheap "toy" models. How important your accuracy and precision are in thsi study shoud be critical in deciding whether to go with one of these models or going with a genuine research grade unit. A geoexploer XM or higher is a few thousand dollars last Iooked. On Sun, May 3, 2015 at 1:52 PM, Jacob Hadle <jjha...@gmail.com> wrote: > Hello, > > I have a question for those of you who are familiar with point and shoot > digital cameras that have built-in GPS units. A project I have acquired > this summer involves a plant inventory on a ~7,000 acres site (open and > dense canopy areas). In part, the protocol requires us to take a picture > of each plant species and document their latitude and longitude > coordinates. To optimizes my time effectively, using a camera that > geotags each picture would seem to work well. > > The main interests I have in the point and shoot camera in not so much > how the quality the picture takes, but how accurate the camera will pick > up coordinates. I have spent a considerable amount of time online, and > calling local camera stores researching which point and shoot camera > would have the best GPS quality; however, I have found very little > information about the accuracy and performance in these built-in GPS > units. I am currently looking into the Canon PowerShot D20 or the Ricoh > G700 SE-M. > > If anyone has experience using digital cameras with built-in GPS units > in the field, I would truly appreciate your thoughts. > > Most grateful, > > Jacob > -- Malcolm L. McCallum, PHD, REP Environmental Studies Program Green Mountain College Poultney, Vermont Link to online CV and portfolio : https://www.visualcv.com/malcolm-mc-callum?access=18A9RYkDGxO “Nothing is more priceless and worthy of preservation than the rich array of animal life with which our country has been blessed. It is a many-faceted treasure, of value to scholars, scientists, and nature lovers alike, and it forms a vital part of the heritage we all share as Americans.” -President Richard Nixon upon signing the Endangered Species Act of 1973 into law. "Peer pressure is designed to contain anyone with a sense of drive" - Allan Nation 1880's: "There's lots of good fish in the sea" W.S. Gilbert 1990's: Many fish stocks depleted due to overfishing, habitat loss, and pollution. 2000: Marine reserves, ecosystem restoration, and pollution reduction MAY help restore populations. 2022: Soylent Green is People! The Seven Blunders of the World (Mohandas Gandhi) Wealth w/o work Pleasure w/o conscience Knowledge w/o character Commerce w/o morality Science w/o humanity Worship w/o sacrifice Politics w/o principle Confidentiality Notice: This e-mail message, including any attachments, is for the sole use of the intended recipient(s) and may contain confidential and privileged information. Any unauthorized review, use, disclosure or distribution is prohibited. If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message.
