GPS enabled PDA advice?

[KBforester]

Hi Everyone,

I was thinking about getting a GPS enabled PDA for map making and timber cruising. I've used a setup like this in the past (big company) with ArcPad, but thats out of my price range while working on my own. Has anyone else used this type of system for forest management? If so, what software? Waterproof case? Bluetooth or plug in GPS? Brand of PDA?

When I was using this type of setup in the past, it was touchy, with lots of bugs to work out. So my nightmare would be to spend several hundred dollars and find out the combination of hardware/software wasn't compatible. Any thoughts?

[SwampDonkey]

I've only been using ArcPad (Version 10 now) and Trimble GeoXm since 2006. It's all the forest companies will except on traverses, need base corrected positions. I've not had any troubles other than user caused, like busting a key on the computer with a puncture wound to let moisture in. That little scrape cost $1300 to replace the receiver and keyboard. DOH!! It's not that bad when you know the repair work will be recovered come tax time. ;) If I were you, I'd keep that in mind when making a purchase. Recouping cost as part of business (Business and Professional Income expense) or conditions of work/employment (here in Canada that's a Form 2200).

I have used Garmin a long time back to do traverses of thinnings. The map was fine, shape and area wise, but it often was not placing it on the map in the right spot, sometimes off by 100 meters. That was using WAAS real time corrections. I do think though that the forest companies put their sample grids on Garmins as well as their silviculture layer because the boss has shown me a couple on his. One map he got and took out to the field on the Garmin, he was standing in water where there was suppose to be thinning according to the way the map sat on the GPS display. So, as I say be aware of those cheapie devices. ;)

[Black_Bear]

I have used Garmin a long time back to do traverses of thinnings. The map was fine, shape and area wise, but it often was not placing it on the map in the right spot, sometimes off by 100 meters. That was using WAAS real time corrections.

I would guess that this error was in the GIS, or mapping software, projection.

We had PDA's bought for us, but our office almost exclusively still uses the Garmins. The PDA's are nice - stand types, aerials, etc. are all right there for you, but up here we found there were durability issues with the PDA in the winter, and we all lost at least 1 GPS receiver, which is the size of a zippo lighter. I guess it is a personal preference what you use, but the Garmins work fine for mapping our cut blocks and are durable in the winter. They upload and download perfectly into Arcview or a Maptech type mapping software.

As with any navigation grade or mapping grade GPS you need to be mindful of the errors and not try to make it do things it can't realistically do. I use the track feature and also stop and take many waypoints during layout. Usually with the waypoints I'll stop and rest for a minute and allow the GPS to cook in the same spot - generally gets a little better accuracy. I'll also take waypoints on features, like a small forest opening, that I can see on the aerial - mainly to check for consistency/accuracy between the GIS and GPS.

[KBforester]

I hear you when it comes to loosing the receiver. I lost one once (in a small otter box), it fell out of my truck in front of the repair shop. I thought I lost it in the woods on my way back to the truck. My mechanic found it in a snow bank in May. Still worked great though!

Yeah, I'm not looking to do any survey quality work, I'm just making harvest maps that match up with flagging on the ground. Sub-meter accuracy isn't necessary. Also in the unorganized townships in Maine, there are a lot of special zoning that I'd like to upload while I'm mapping. The thimble looks awesome, but way out of my price range.

[SwampDonkey]

I would guess that this error was in the GIS, or mapping software, projection.

I wouldn't make that guess because it didn't always happen to be off, but I did find some traverses off the mark when both Garmin and Trimble were used together on a  block. Which is true, the Trimble screen showing your cursor on a marked boundary as your looking down a line of tree spots through the woods or Garmin showing the line on the screen, but when looking in the woods you see no spotted line? ;)

When it comes to mapping cut blocks however, they are fine as you say, because the logger is paid on volume of wood. They are also fine for cruise plots and density sampling plot locations in my opinion. Although, there are some that like to count plots in ditches and harvest trails of raspberry canes and have to sense to just drop most of them plots out. It don't look good on a 8 ha block to see 7 plots land in zero counts and see just 4 steps in either direction would yield 30+ trees for 30 or more meters. :D However, when mapping silviculture treatments that yield no volumes, a little more accuracy is called for since your paid on acreage treated. If I cut brush I want to be paid for every inch of ground I swing that saw over. ;) The worst thing however, is that those cheapie GPS allow you to stand within 10 m of the mark and call it plot centre, each time you go back with them the position changes from here to there. :D



This shows about half the plots in zero counts (trails, road side slash, perimeter trail). Now I ask ya how can half the plots be zero plots and that area in zero count zones isn't anywhere near half the total treated area? We aren't allowed to count the perimeter area unless there is quite few meters beyond it to the big woods. Nor can we count road side slash in the area. In this case the perimeter ribbons are on the south end of the northern perimeter trail. We can get some of those zero plots thrown out if we take down plot numbers, but we have to call them on it. Otherwise, we get robbed because of low density due to serious sampling errors. And if anyone wants to claim you can just walk right to the spot with them Garmins without the screen cursor moving all around 10 m, I will have to watch this one. Better at least have a good 3D lock. :D I know right off the bat, if more than 20 % are zero counts, I've been robbed.

We are on a new block now, and I'll take pictures of the site to show you what we're up against. Already the boss indicated he has a conflict with their rate. : Outside of the harvest trails, which by the way need cutting out because of hardwood, it's a solid green wall 3-5 meters tall. Underneath that shade of green is nothing but a carpet of shreber's moss. Nothing for even a bee to draw nectar from. :D :D

[SwampDonkey]

One fellow I know left a Garmin on his pickup bumper and traveled a mile or so down the road, got out and it was still on the bumper.  ;D :D :D

I've never lost a Trimble because it doesn't leave my hands. And I have a procedure at work I follow like a guy working on an assembly line. Follow it and you know where stuff is. ;) I'll draw the line on further commenting because I don't want to make insults. ;) :D

[woodtroll]

I used a garmin and a palm as a consultant. Now I like the DeLORME pm 40 I can up load photos, topo's or any other maps plus shape files. Comes with its own mapping programor can work with arcmap. The trimble is more accurate, but runs many thousands more plus the software. It just is cost prohibitive for most aspects.

[SwampDonkey]

Magellan sells a handheld GPS (Mobile Mapper CE) with post processing software and GIS included. It's not cheap, but less than a Trimble.

I say if you factor it in your business expense Trimble GPS cost is recouped at year end on your expense claim during tax time. I guess it depends on how busy you are as a consultant. I've used my current GPS to traverse 600 + acres a year since 2006 including work strips. Paid for itself the first silviculture season. I actually started using these gadgets in 2000, Trimble, Garmin, Panasonic. If you educate yourself a bit about databases you can write your own data logger and cruising programs like I have. Come back to the office and connect to your PC and download the data, or beam the data through Bluetooth to other field crews and such.

Mobile Mapper 6

The Delorme pm 40 looks like a nifty one woodtroll, the 60 is out now. I don't know what is involved in getting that data into the unit, for me on my GEOXM there is no file conversion required. And we have to submit shapefiles to the forest company and private woodlot associations. Arcpad on these devices makes life so much better because you can edit vertexes by using the "Move to GPS" feature. Otherwise on other systems you have to retraverse sections if editing is required and piece all the mess together. : The boss just says, "fix this" :D :D because his GEO3 does not have the same editing capability.

[woodtroll]

The PN 60 looks real nice I have not got my hands on one yet.
Putting data on is simple. You can use your own data or download from their site.
I set some up for our rural fire fighters. I put the county photos and usgs topos on. Property lines for all the landowners (with owner's name). Township Range Sections and quarter quarters. All the government ground by agency. Plus the Delorme base data which is pretty good. Stands lines and way points are easy to put on. And all the data is set in layers so you can turn on or off the info you need. It has work pretty well for us.