GIS-Where to start?
The State Trails Coordinator who oversees the park I where I build trails has asked me to submit my trail build and reroute proposals in a shapefile. I didn't know anything about this, but Wikipedia tells me this is the output of a GIS program. The biggest commercial program is ArcGIS
What Is GIS? | Geographic Information Systems
but they are out of my price range at $2500 per year for 5 seats.
In the freeware world, there are many, many choices. It looks like GRASS does most things, has a fairly large user group, and is decently supported by the developers.
GRASS GIS - Home
Does anyone out there in the trail building world use this type of program? If so:
-Does GRASS look like a good program for my needs: A way to place waypoints and tracks over a scanned map, and maybe an aerial survey map, and possibly someone else's (the state DNR's) imported shapefile for my park?
-Is GRASS way too much program to learn for someone with limited time to devote to the project? I have to build trail and work a full time job and live a life. Maybe some other program would be simpler and more suitable to my needs?
I have used GarTrip previously
which is fairly simple to learn. It imports tracks and waypoints and will plot them over an imported, scanned map. However, the output is in .xps format, and is a pain to import into any other program. It definitely does not output .shp files.
GRASS does work very well, but it's a command line environment. If you're not comfortable with that, you might not want to use it. Instead, I'd suggest Quantum GIS or MapWindow GIS. Both are open source programs with a graphical interface. QGIS includes GRASS but some of the more common tools have graphical interfaces that make it a little more user friendly.
Also look up DNR Garmin. It can convert your .gpx files from your handhelds to shapefiles if all you need to do is convert, although QGIS will plugin with GPS Babel, which can do the same thing.
Also, shapefiles are a collection of separate files that each tell something different about your spatial data. You will have to zip them all together for submissions, lest you leave out something important and break the file. They're a little clumsy in that way. Be glad your coordinator didn't want submissions as geodatabases. Much cleaner for sharing, but MUCH bigger learning curve.
Thanks Nate, your reply is most helpful.
If your a Non-profit you can get ArcGIS for $100!!!
Epic trails get built in the Northwest by epic people!
Sustainable quality trails please.
If you are only submitting line data as shapefiles, I would stick with Google Earth for any minor editing and DNRGarmin to do your conversions to shapefiles. Keep it simple. You only need ArcGIS if you get into making maps or doing other complex spatial analysis.
1. Download GPX - Google Earth/DNRGarmin/GPSBabel etc...
2. Work in KML Format - Google Earth
3. Convert to SHP - DNRGarmin
Practices to Make Your Life Easier:
- When you are trying to create a track with your gps, make that the only thing you are doing so that the line is clean.
- Find the sweet spot in how many points are collected. There is no need for one every foot and 200 ft might be too much.
- Make sure you have good data before you start tracking.
- Use an organized naming/folder structure
In reality, the trails coordinator should be able to handle gpx and kml files with ease. It is literally a 30 second conversion.
For the most part, I'd agree. However, I'd disagree on point frequency. I go with the most I can. For proposals, I only go with one pass along the route, especially if it's flagged on the ground, since the proposal is just a suggestion anyway. For mapping what's already there (say, mapping the reroute after it's completed), I go with a minimum of three passes, overlay each track on the screen, and hand draw the final route based on a combination between agreement between tracks and what's visible in satellite imagery.
Originally Posted by justinwp
Sometimes, the trail is visible in the satellite image, so the GPS tracks can be superfluous unless there's high agreement and not aligned with the sat image. Sometimes, all of the tracks have a high degree of agreement and I just trace them. Sometimes all of the tracks diverge a lot. In those cases, if I can't see in the satellite image where the trail should be, I might go back and collect averaged waypoints along the route to try to pin down the precise location of the trail. All mapping is done by walking so track points are laid down in a high density so outliers can be easily identified and have the least effect on the track as a whole.
Thanks for all the good ideas. I had no idea ArcGIS was available with a discount to non-profits, I will look into that.
I appreciate the process notes. Up to this point I had been taking waypoints and sketching in by hand. Good enough for my use, but this probably isn't what my land manager is looking for. I think what you guys have outlined is closer to what she wants. I'll go back and walk off my flag line, then import the track(s) and attempt a conversion.
Over the longer haul, I would like the capability of generating my own maps. My club provides maps of our various trail systems on our web site. I have been using a scan of someone's gps tracks to produce maps that get mounted at the trail head and at major trail intersections. I've also been tasked with making a system of trail posts and numbered markers. The idea is that the marker numbers can be called into the park ranger or local ambulance services for the rescue of an injured, immobile rider. I've issued my first map for the main trail loop with an accompanying table of trail markers to the relevant parties, but have miles more of trail to sign and map. I want a system that can be easily modified to accommodate the trail reroutes we will be constructing in the future.
The immediate need, however, is to get my proposals to the land manager so we can get some work done this spring. The mapping will come later.
I've used QGiS a bit and it's pretty good. In many ways I prefer it to ARC, but ARC also does some things QGIS doesn't and vice versa. QGIS has lots of extensions that make it really very good.
As for collecting GPS tracks, as long as you don't expect better than 10-20 meter accuracy then just go with one pass I reckon. Taking the odd averaged waypoint (minimum 50 fixes has been shown in Uni research to be about the point when it gets worthwhile averaging) helps in areas that need added accuracy. Also adding an external antenna and, in my experience, a groundplane makes quite a big difference when working under tree cover.
I use a Garmin (76cx - cheap, but good receiver chip) with an external antenna with a 6 inch circle of aluminium flywire under it. I have a small piece if steel bungied on top of my helmet, the fly wire goes over it and the magnetic antenna clips it together. Makes a very noticeable difference to signal strength. Bending the edge of the circle up a bit also seems to help reduce multipath effects (google it if you care). Cheap but effective. I also run a Trimble GeoXT professional grade receiver, but it rarely gets a run on the trails as it really doesn't like the poor signal under trees.
Also don't assume that because google aerial looks nice and sharp, that it's accurate! Around here it's out by a good 30 meters. Bing is better for us, YMMV.
I second DNRGPS for converting tracks to shapefiles.
Originally Posted by mtbty
Our group got it this way. (grant)
Of course, then it's "now what?" as it's a hugely intense program. We got help from the local university, which teaches it, and from a prof at the CC who was well versed it in. We learned how to do the specific tasks that we needed to do, and built on it from there. We put the software on a laptop so we could take our project to the various folks for assistance. At one point we were told we were past the 1st year students, yahoo.
We got community assistance in other ways too. The CC prof had her foresty students do a lot of our mapping for us, using their uber-sensitive GPS units. Then she helped us use the data in ArcGIS to further our map project.
I agree, this may be the best route. What about contacting a local University and talking to one of the Profs in the Civil Engineering department. They usually teach classes on surveying (via GIS these days I'm sure), probably have a Trimble GPS unit in house and there might be a student who would be willing to support as part of a Community Service project.
Originally Posted by formica
Your state TC wants a shapefile, but shapefiles can have various coordinate systems and datums. That's one of the more difficult things to grasp for those new to GIS. QGIS and I expect ESRI (ARC) open .gpx directly and make datum conversions on the fly, so I'm surprised that he can't work with .gpx which has become the most common filetype used. Beauty is that with gpx there is only one CS/datum, so no possible conversion problem.
For any number of reasons, QGIS is worth at least a tire kick. If the TC wants a shapefile, I'd expect that he may overlay your trail with other shapefiles with regulatory significance like wetlands, vernal pools, mapped habitat, boundaries, etc. It's highly likely that these datalayers are available to you for free. If you have all this info with your trail on a map, it can give you a leg up on project approvals and help avoid areas that are problematic.
Ahh, good point about the coordinate system. I hope to get feedback on my submission to deal with such problems.
Originally Posted by ramshackle
I checked the state's DNR map respository and did not find anything for my park, but it could be under some other, more general survey.
This has been the main problem I've experienced with using tracks to make maps. 10-20 m error causes the trail to show up with obvious errors such as going outside of park boundaries, crossing existing trails, etc. But combining tracks with averaged waypoints should help.
Originally Posted by BikerPeteOz
Yes, this is exactly what I was concerned about. I think I have enough ways to submit the requested shapefile(s) in time for the spring build season, I'll look for help in the meantime for the more involved mapping that I need to do late in 2013.
Originally Posted by rogerfromco
The latest version of GRASS (6.2?) does offer a graphical interface. It still may be too much program for me to learn quickly enough, thanks for your alternative suggestions.
Originally Posted by NateHawk
I will throw myself in front of the bus here and recommend checking out Global Mapper. It's not as powerful as ArcGIS, but is much more user-friendly for simpler applications like trail mapping. Additionally, anything you do in Global Mapper can be exported as a shapefile and then opened in Arc, so you don't have to worry about other people not being able to use your data.
Also, try to get your hands on 1-meter resolution aerial imagery as well as LiDAR (Light Detection And Ranging) data if it's available for your area. Most elevation data is either 10 or 15 meter resolution, while LiDAR often comes in either 1- or 2- meter resolution. This gets you much more accurate elevation data. In a map I'm working on now, I have been able to just trace out logging roads and double track just from the elevation data; the skidder tracks left ruts 20cm (8 inches) deep that show up on elevation data. SUPER ACCURATE! Oh, and that's even in a densely-forested area, so anywhere. It's not available everywhere but if you can get LiDAR data it can make your life much easier.
GIS-Where to start?
Lidar coverage is very spotty. It is more common in logged areas because it is also used to analyze forest structure. 30m elevation data remains the most widely available but some areas have better stuff...10m or so. Depends on the state. Still not good enough to identify trails.
IMO, every trail club needs at least one GIS person. Short of that local colleges/universities are good places to find help. GIS departments do not always appear in the same parts of campus. Sometimes they are in geography and sometimes elsewhere. Where I just graduated it was in the college of forestry and agriculture. We even had our own IT people separate from the rest of campus.