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Apr 09 2012

First Test of PVC Markers


On Thursday 4/5/2012 Jonathan and I went to HR with 2 other students to attempt to lay out the PVC pipe that will mark the 5x5 meter grid. Our plan was to lay a reference string between 2 of the serveyed points in the 25x25 meter grid. Once this was done we could measure 5 meters along this line with our wooden poles, string, and line levels to help ensure accuracy. We secured a string between the two wooden poles measured at 5 meters We would than insert PVC poles like the ones to the left at these 5 meter marks. However when we finished our first 4 points and came to the known survey point we were anywhere from 10 to 30 cm off. This was too much inaccuracy and we quickly saw that the string connecting the two wooden poles could flex, this being our cause of inaccuracy, we determined we needed a more rigid material to connect the poles. Back at the lab we found some thin metal wire and after attatching this to the wooden poles and retesting the same strategy as before the accuracy was greatly improved, at most we had a 1 to 2 cm innaccuracy with most of the corner points we plotted landing directly on the survey point.

Mar 27 2012

Topography and the Mapping Grid

There has been a new data sheet designed to address the specific needs of the forest we are working with. Because the method for mapping the trees has changed, the data sheets also needed to be altered. We are returning to the previous used method of laying out a 1x1 meter grid within our 5x5 meter grid. Once this is complete the location of the trees will be marked on the graph found on the data sheet. There has also been a "codes" column added to the data sheet to represent trees that may need special attention. This could include a leaning stem, a stem broken below breast hight, or as seen in the picture multiple stems from one trunk forming below breast height. However, before the trees can be mapped the grid must first be sectioned into 5x5 meter squares. Jonathan, fellow students, and I are hoping to get one of the 25x25 meter plots sectioned off so we can begin to test our tree mapping stratgies. We are also tackling the problems we may face concerning drastic elevation changes. In summary we have all of our supplies ready and in bags we just need to find a time to get dirty and see how our ideas work.


 

Mar 21 2012

Tree mapping Technique

There have been many methods for mapping the trees within our 25x25 meter grid that we have identified. The one certatinty we have decided on is the grid must be sectioned into a 5x5 meter grid before we can begin mapping. The picture on the left shows a method found in the field guide Methods For Establishment And Inventory Of Permanent Plots. This method involves usining geometry to determine the exact point of a tree and we thought it could be more accurate and faster than other ideas. However when we went to our forrest to test we discovered that it was not only more tedious but may not improve accuracy by a reasonable amount if at all. The problems arose when we needed to take measurments on unlevel surfaces. It would involve 3 or more people with much instruction and using handfulls of equpment, it was uneffective for our purposes. We plan on going on another test run before the week ends to try another method that will hopefully work for what we need. 

References:

Dallmeier, F. (1992). "Long-term monitoring of biological diversity in tropical forest areas." Methods for establishment and inventory of permanent plots. MAB Digest Series, 11. UNESCO. Paris

Nov 11 2011

GoPro HERO 2 in hand, now I just need time!

OK, so now I have a new GoPro HERO2 camera shooting 11MP stills at 2fps, I just need the time to go out and test it at our study sites.

First things first, this camera is shooting stills with relatively wide field of view (FOV) and we don't know what that is going to do to structure from motion computation.  The camera shoots in full 170º FOV in 11MP and full or medium 127º FOV at 8MP and 5MP.  Narrow, 90º FOV, options most similar (although still wider) than the other cameras used in our research, are only available in video mode.

Some initial tests with ground subjects on campus have produced somewhat positive results, I think it is too early to tell for sure.

More to follow, when I can get to it.

Apr 02 2011

Battery Configuration Test

In an attempt to increase the EasyStar’s endurance we had decided to place two 2200mAh, 11.1V battery packs in parallel with one another. One of the major concerns in doing this was the possibility of overloading the plane’s frame and altering both its flight characteristics and inherent stability. Earlier today I had decided to test the EasyStar’s ability to handle the additional weight of a second battery pack (approximately 179g) as well as test the parallel battery cable that I had made a few days earlier.

As expected, the additional weight in the plane’s nose had significantly changed the EasyStar’s center of gravity. To account for this the camera mounting position was moved further back and is now located more than 75% of the plane’s length from the nose. During this test flight the camera was replaced with 165 grams of washers. Overall the EasyStar had handled the additional weight with ease and was actually a bit easier to manage in flight. Full throttle along with a solid throw is now required for an adequate hand launch and the elevator must be used gracefully in order to prevent the wings from breaking when pulling out of a dive. Although the stall characteristics were a bit less forgiving with the added weight the plane was still able to maintain a level flight after both tip and power-off stalls at the cost of a significant loss of altitude. The EasyStar’s gliding capability was greatly affected and sustained gliding via thermals are no longer possible. The most significant difference between the new and old setup was the change in landing speed. the EasyStar must now be landed at much greater speeds to prevent damage to the fuselage. This means that extended flights with two batteries will be limited to areas with larger fields nearby for landing. Sites like Herbert Run would be very difficult if not impossible for this configuration but the Knoll could still be flown due to its close proximity to large open fields. Endurance test will be flown within the next few days along with a one square kilometer mission.