I am attempting to start a new project to understand where roads are barriers to amphibians and reptiles. I’d like to collect observations of these animals but limit it to observations made at or near roads. Is there a way to set parameters within a project to ensure that only images taken at or within 50ft of roads are included? Thanks!
One problem with a criterion like “within 50 feet of roads” is that nearly all observations come with some sort of uncertainty bubble, and if the bubble extends beyond the boundary, the observation won’t be included. With a boundary that narrow, almost no observations would be included.
One work around if this is a research project would be to download ALL potential records and then use the coordinates (without uncertainty bubble) in standard GIS to filter for those within 50 feet of a road.
You’d still have the problem that GPS coordinates of an observation are the coordinates of the camera, not of the subject, but that’s probably trivial.
I would be possible to create a shapefile/boundary file that is a 50ft buffer around roads, assuming there is a shapefile for roads already (which would be a safe assumption for many countries), but that polygon would be very complex and large depending on what area you are looking at. I think that upper limits for places are 1 mb for users and need to be smaller (in terms area) than the state of texas. So if you are only interested in a specific area, it could be possible, but the entire USA for example would potentially be too large/complex.
As @janetwright pointed out, 50ft is quite small though… and increasing this area would make the shape larger and more likely to be too large for a place.
I agree that downloading the data and filtering in a GIS program (arcGIS, R) to select only records within the buffer distance would be the best work around, but it requires knowledge of those programs.
I agree quite a few observations would not be included, but I just want to clarify that it’s the bounding box that’s the cut-off, not necessarily the boundary itself. The bounding box is the rectangle that inscribes the entire boundary. Take this place for example, which is a river. In red I’ve drawn an approximation of the bounding box:
The uncertainty circle/obscuration rectangle of the observation would have to break that rectangle in order to prevent the observation from appearing in the place (provided that the observation’s pin is in the boundary itself).
I do agree that a traditional project is probably best for something like this, with perhaps extra work like @jacksonkusack suggested.
at least where i am, if an observation doesn’t occur within a known park or within a major metro area, chances are good that it occurs near a road. (you can actually infer where roads exist based on where observations occur out in the boonies.)
I am trying to set up a Project for the first time. (I have more than 100 “research grade” observations.) When I get to the Set Up Map page, the map comes up, and I zoom in to my project area …but I don’t get the visible buttons that I must click to get the tools to draw my Project Space on the map. Can you give me any advice?
Are you seeing instructions that show those buttons somehwere? If so, those instructions should be updated. The “official” instructions are here, but maybe there are outdated instructions elsewhere. Happy to fix them if I can.