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May 02 2012

First Group Field Day

On Saturday 4/29/2012 we had the first field day of the semester. The goal was to begin mapping the trees at HR and to perfect our methods. However we soon discovered that our 5x5 meter plots that had been previously marked with PVC had much more error than we anticipated. To accommodate this we mapped the trees in the corners of 25x25 meter plots because they contained the known survey points.

We managed to get 8 of the 5x5 Meter plots surveyed and ready to document. Also, we have determined a new method to plot the 5x5 meter subplots. Our error came from one main source. When we were measuring the 5x5 subplots we started by marking the perimeter. Once this was done we laid out a string across the plot and measured along the string to mark our subplot points. While the points were 5 meters apart in one direction they were not in the other. The reference string did not provide enough accuracy and would lead to a line of points which fall to the left or the right of where they should fall.

To tackle this problem we purchased a straight line laser that can shoot up to 1000ft. The idea behind this is it will give us a perfectly straight reference line. We will shoot the laser across the plot from one known perimeter point to the next and than proceed to mark the points within the plot that lay on this line. This will hopefully do away with the error that accumulates while measuring along an inaccurate reference line.

At the end of the day we learned allot about our methods and what needs to be improved. This is all a part of field work to design, test, and redesign. Hopefully we will have another group field day soon with corrected subplots allowing much more mapping to be accomplished. I want to thank everyone from the ecosynth team and volunteers who made this day possible. 

Apr 25 2012

Finishing up Herbert Run

Saturday April 21st  , Shelby, Dana and I went out to Herbert Run and were able to get a lot done in in the field. We were able to set a decent amount of control points as well as make progress during the stake-out by obtaining roughly 8 more points. The points we were able to get were the ones on the far Eastern edge of Herbert Run 168-175. This leaves us with about 8 or so points left that need to be mapped out and I am convinced that with Dana's help today and a little help Friday that I will be able to complete the Survey either Saturday or Sunday at Herbert Run. Then next week I can do the complete Survey for The Knoll.

This data collector is helping a lot. At Landesign Inc. the data collector I used was no where near as nice as this one is. It can connect to the internet, which could make stake out really convenient. As displayed in the picture on the left the Trimble actually pulls up a complete map of the Survey that I will do. The points you see on the screen are the ones that I have loaded in. It also has my control points which you can see towards the top left of the screen as point numbers 4004 and 4005 These are my traverse 1 and traverse 2. This will be how I establish my traverse loop which because of the small size will probably have quite a small amount of error.

I am considering using existing control at Herbert Run to create control at the Knoll. Since I have specific coordinates for the traverse at Herbert Run I can use those to Run control down to The Knoll. This just means that I will have two traverse loops obviously the one that connects HR to the Knoll is far larger than the one that will be specifically for HR, which entails more error but we can distribute that error evenly throughout the loop and it will be fine.

Finally I am going to need to create the Grid points in GIS this week for The Knoll so that Monday I can get started on that.

Dana also had a great idea when we were out in the field she proposed that we use the GPS to guide us to the points that we are trying to survey. Sometimes these points are in the worst locations such as the points around 170 in Herbert Run and it can be a major hassle trying to read the map and decide what direction and how far is needed to pace to the next point. With the GPS we could get a much better rough estimate of where the next point to be staked out is, for those points that when using the map and actually walking through the forest are impossible to just pace to. This is the situation for large fallen trees in the way, large increases in elevation and streams.

Apr 17 2012

Rendezvous with Brian Wagaman

I was able to get in touch with Brian Wagaman on Friday April, 13th 2012. What we had landed on was that I will meet him at Keystone precision on April 19th, 2012. I sent Brian Wagaman an email of Dr. Ellis email regarding billing for the data collector rental. When we get together on Friday Brian has agreed to instruct me on how to establish a network of control points via the traverse method with the data collectors that Keystone has available. This instruction will be completely free, the only charges will be for those of the data collector. I was going to ask if it is ok to take the instrument home Friday at the meeting Wednesday, Brian and I will use it for a couple hours then on Saturday I will work a twelve hour day Surveying the Bananas out of Herbert Run. I will need two volunteers for two shifts because I do not think anyone person should have to help me for more than six hours. the week following that I will have a gap between exams that will allow me to do the Knoll so it would be best to rent the data collector from Friday April,19th 2012 up till Monday April 30th that way I will definitely have ample time to finish the survey. 

I believe that this will dramatically increase productivity because I will not have to wait on control points. It will speed up the process ten fold. The survey of both the Knoll and Herbert Run should be complete by 4/30/2012.

I could have met up with Brian on Monday but I was swamped with two exams this week therefore I thought it would be best to rent the data collector for a short amount of time instead of just having it while paying for it and not actually using it for any surveying work.

Apr 11 2012

Herbert Run West Surveying & Keystone Rental -- Updates

Saturday April 7th, Shelby and I went out to Herbert Run to stake out some more points on the western portion. We were able to get seven points that are all in the area pictured on the left. A lot of this area was really difficult to get because of the amount of brush that was online but we were able to get them all from a one of the new points that Will had RTK GPS located.

I went to Keystone Precision this morning to ask about renting data collectors, it turns out that they do rent out data collectors and they also give out software packages for them. The rates seem fairly inexpensive at $42.50/day, but they do not rent out prisms. I explained our situation and the sales representative generously said they would let us borrow a prism if we rented the data collector.

The data collectors are called the Ranger, which has a software package called Survey Controller and the TSC2  which has a software package called Survey Pro.

They also had an option to rent an entire total station plus rod set up for $120/day.

The representative at Keystone said that if I were to talk to Brian Wagaman I would be able to have a lot of my questions, (such as information pertaining to the stake out options of the data collector ) , answered.  I vaguely remember the survey company that I used to work for, Landesign Inc, were really big fans of Brian Wagaman’s help with total station questions and data collector trouble shooting issues, he is really approachable.

I believe this is the best way to proceed and hopefully we can rent the data collector and software for this weekend so that I can finish Herbert Run and the Knoll. I can call Brian tomorrow about the data collector rental and hash out the issues with him.

Oct 25 2011

WiFi 1.5-mile range: never lose signal in the forest again?

WiFi for Ecosynth?  Amped Wireless Unveils Its Professional Series High Power Repeater and Access Point with Wi-Fi Coverage Range of Up to 1.5 Miles

Amped Wireless unveils its professional long-range Wi-Fi Access Point and Repeater that provide Wi-Fi coverage for large homes, offices, building-to-building applications, open outdoor areas, boats, marinas, RVs and parks.

CHINO HILLS, Calif., Oct. 24, 2011 /PRNewswire/ -- Amped Wireless, the leading manufacturer of high-power, long-range wireless products for the home and office, adds to its successful line of Professional Series High Power Wi-Fi Solutions for indoor and outdoor applications. All Amped Wireless Professional Series High Power Wi-Fi Solutions feature a weatherproof enclosure for indoor and outdoor use, an advanced 600mW amplifier for professional Wi-Fi range, and a high-gain directional antenna to achieve strong, wireless connections up to 1.5 miles. Amped Wireless Professional Series

Jul 18 2011

XBees Again

I think I have fixed the XBees, again, maybe…

I wanted to get our tablet laptop up and running again as a Hexakopter flying machine for the field – especially since I got the new Pentax WG-1 GPS camera in the mail today (I’ll post on that soon).  This laptop had already been running Mikrokopter-Tool v1.74a, allowing us to do 3D waypoint runs, but the XBees were not functioning at all.  I also had it in my head to install a SSD hard drive in this old laptop to give it a new lease on life – what better opportunity to try a fresh setup! 

A quick note to anyone that has found their way here with their own XBee woes, we are using XBee Pro DigiMesh 900 modules.  This post discusses the (hopefully) successful configuration of a pair of XBee Pro 900’s each mounted on an Xbee Explorer USB.  In a previous post, Xbee Solutions?, I suggested that it is necessary to have an Xbee Explorer Regulated on the MK end, but it seems that may not be necessary based on the results described below.

I got all the standard drivers and software installed and running (XCTU and  UART drivers) and plugged in the suspect Xbees.  Windows 7 said it correctly installed the new hardware, but when I opened up MikroKopter Tool I could not get any XBee communication. AAAAAAAH!

Back to the internet, I found this long thread about Xbee problems that offered promise: http://forum.mikrokopter.de/topic-21969.html

Taking from the thread, I set up two XBees on the same machine in two instances of XCTU to be able to effectively range test and compare parameters. Why had I never thought of that!? I read the modem configurations from each unit – mostly noting anything that was other than the default and confirming the baud rates were set correctly.  I quickly noted that the Modem VID numbers were different and read from the help dialog: “Only radio modems with matching VIDs can communicate with each other.”  One XBee was set to the default and another was set to a specific number.  I didn’t remember making this change but decided to set them both to the same number.  The range test was now working perfectly (see post picture).  Back in Mikrokopter Tool I was back in business with wireless telemetry, but I still couldn’t transfer waypoints.  I kept getting that ‘Communication Timeout’ error.

I tried another suggestion from this  post  in the same thread and manually adjusted the Destination Addressing fields on each unit.  I noted the high and low serial numbers for each unit (SL and SH) and manually configured the  high and low destination addresses to point at each other: XBee1 DL = XBee2SL, XBee1DH = XBee2SH, and vice-versa.

I flashed these settings, booted up MikroKopter Tool and was wirelessly transferring waypoints and receiving telemetry with no problems.

Of course, now we just have to see if it’s actually going to work in the field!

Next up: playing with the GPS camera!

Mar 03 2011

New Field Equipment for 3D Forestry

Our new forestry mapping equipment is going to make collecting 3D tree and canopy data a lot easier!

We recently acquired a Trimble GeoXT GPS and TruPulse 360B laser range-finder for use in our forestry field data collection work.  The GeoXT is a high grade mobile-mapping, mobile GIS, GPS unit that offers sub-meter accuracy after post-processing in the lab. 

By itself this would allow us to collect sub-meter (0.5m – 0.7m) accurate positions of tree trunks or other features on the ground.  The TruPulse is used for measuring distances and heights using a built in laser and inclinometer that automatically does all that pesky math that would be needed when using an analog clinometer.  The 360B model has built in Bluetooth communication, which means that with a little configuration in the lab the unit can wirelessly beam positional and height data to the GeoXT.

This combo is used for ‘offset-mapping’ where the user stands in one location with both GPS and laser in hand and by using the laser is able to map to the GPS the XYZ position of other objects that are not nearby (typically less than 200m based on the power of the laser).  For us, this means I can map the position of tree tops in 3D space and automatically record the tree height to the mapping GPS with relative ease and greater precision than when using paper and pencil field notes.  This type of data collection is necessary for the calibration and validation of Ecosynth 3D point clouds, http://ecotope.org/ecosynth/methods/ecology/.

We will roll out this tech in the field in the coming few weeks as we move into the growing season, but in the mean time my initial results suggest that this will be a high-quality approach for mapping the position of tree crowns, a vital and challenging task.

The photo below doesn’t look like much, but it shows a sample of some of this 3D data.  This is an oblique shot looking through a 3D point cloud of the Knoll at UMBC.  The yellow area at the bottom is a digital terrain model of the land underneath the canopy; the blue points are the Ecosynth 3D point cloud of the site; and the red points are 3D points of tree tops and tree base mapped using the GPS  / laser combination.  This screen capture doesn’t do it justice, but trust me when I say that it looks good in 3D!

Hey Evan, are you sure you don’t want to come back to continue the forestry work?

Feb 23 2011

Hexakopter Suspended Payload Tests–Results

The results of our Hexakopter payload tests were better than expected!

You can see a few clips from the test flights here: http://www.youtube.com/watch?v=OZlamfvl3VU

Basically, we suspended a 1.5lb weight from a metal cable, dangling about 12 feet below the Hexakopter.  We tested take-off, landing, auto-controlled hover with GPS and altitude lock and waypoint flying.

We found that the onboard computer can fly the unit with payload better than I can and that it performs very well at staying balanced despite a pendulum effect from the payload.  The unit appears to dampen this effect after a few seconds and in periods of calm wind the whole rig appeared virtually motionless.  In an auto-hover test, the unit lasted about 12 minutes before reaching the battery limit, it is expected that this time would be a bit less in a real flight.

Overall, a successful experiment and a great day to be out in the field!

Feb 17 2011

Hexakopter Suspended Payload Tests

How well will a Hexakopter work at carrying an instrument payload suspended several meters below?

That is the question we will be trying to answer in the next few days as we get ready for some work for the Forest Service. The goal is to suspend an instrument payload several meters below the Hexakopter on a light-weight metal cable. The payload will weigh about 1.25 lb (0.56 kg) and needs to be far enough away from the Hexa to avoid the effects of downward prop wash. The payload and Hexa will be flying through smoke and we want the instruments to be unaffected by the Hexa itself.

I purchased some 1/16" (~1.6 mm) braided metal cable, some ferrules and some clips from the local hardware store to build the suspension system. I am going to use a 'calibrated' water bottle in place of the instrument payload for weight.

I am going to test:

1) At what distance below the Hexakopter will the effects of prop wash be non-existent / negligible? This will be done in the field by flying a Hexa above a pole with flagging tape on it. This distance will be referred to as X meters.

2) Can the Hexakopter fly in manual and auto mode with a 1.25 lb payload suspended at X meters from a 1/16” metal cable? This will be tested by performing take-off, manual flying, auto-hold, auto-waypoint flying, and landing with the payload attached. Results will suggest total success or a range of flight performance. It is expected that wind will play a significant factor.

3) How long can the Hexakopter fly with the payload attached? This will be tested by first getting the Hexa to altitude with payload and letting it to hover until the battery is at the minimum safe capacity. Then, with a fresh battery installed, it will be tested by flying a simple ‘back and forth’ route over the flight area to simulate increase battery demand.  It is expected that there is a great potential for pendulum affects to occur during flight.

Stay tuned for some results!

UPDATE: I forgot, one of the main Hexakopter videos shows Holger doing his insane Hexa flying witha 1kg soda bottle suspended from below.

http://www.youtube.com/watch?v=gvH2f-AewX8&t=8m0s