Tag: Visualization

Negative space

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400 rolls of film from the 1970s.

400 rolls of film from the 1970s.

In the 1970s I exposed about 400 rolls of black and white film. Most of these were 36 exposure rolls of 35 mm Kodak Plus-X which I bulk loaded and developed at home. I made an 8 x 10 inch contact print of each roll, and put an accession number on the contact sheet and the glassine envelope with the negative strips. I still have all 14,000 of these negatives and contact prints. If you think that preserving this collection suggests that I am farsighted, consider that I never put a single date on any of this material.

Kite’s eye view

In the late nineteenth century, hand drawn “bird’s-eye maps” were a revelation to earthly New Englanders. When exotic hot air balloons were the only way to gain such a perspective, enterprising artists just imagined what a bird might see. The customers for these maps lived and worked in the buildings depicted, so these are probably placed with some accuracy, relying on existing maps for data. It is the details of the rest of the landscape that were recorded nowhere else. In the 1889 drawing below, cleared fields, orchards, and shrubby growth nearly to the top of Hogback Mountain confirm the wisdom that in 1850 the entire slope, like others all over Vermont, was probably cleared of trees. Today, the young ages of the trees tell the same story, but an old bird’s-eye view is still a revelation.

Sprucing up the hills

The Fled overflies as I reel it in.

The Fled overflies as I reel it in.

It has been 14 years since we set up our first study plots south of the Alaska Range. I just returned to Fairbanks from a week-long trip to re-census the plots located above the upper forest limit at the Canyon Creek and Monahan Flats sites. There were a few scattered spruce trees and a total of a few dozen spruce seedlings marked with numbered tags in the quarter-hectare plots in 1998. The trees have not changed much, and only 8 to 10% of the seedlings have died. The surprise was the number of new spruce seedlings that have established in 14 years.
NIR/VIS KAP rig

The NIR modified and normal A495 cameras with AuRiCo controller. Synchronous, vertical photos were taken every 16 seconds.

Seedling density increased by a factor of 2.9x at Canyon Creek and 2.2x at Monahan Flats. The similarity between the two sites suggests that the seedling invasion may be widespread. These seedlings have a lot to endure before they become trees, but if similar numbers of seedlings continue to establish and many of them become trees, these plots will no longer be above treeline in 50 years.

I was able to get some aerial photos of most of the plots after I had marked each seedling with pink flagging. I flew a dual camera KAP rig with normal and infrared-modified cameras lofted by a kite. I will be experimenting with false color IR (NRG) and NDVI images which can be created with information from both cameras.

Unexpected Panorama

KAP over the Kame terrace from Petri's field

Note the Henry's Handle hanging from the belt. The kite line is cleated to that while I attach the Picavet and run through the pre-launch checklist.

The huge kame terraces in my town support a dry-tolerant forest of oaks, beech, and red maple, and as the new leaves emerge it is easier to tell the species apart at a distance. So I have been hoping to fly a kite over the terraces in early May and see if the trees delineated the terraces. The wind was gusty today, but it was supposed to calm down a bit in the afternoon, so I hiked up the hill and launched the nine foot Levitation delta. It was after 6:00 PM when I first triggered the S95 with the Futaba transmitter, and the light was wonderful even if the wind was not. It mostly cooperated until it slowed down enough to send me running upwind barely fast enough to keep the line out of the trees. But I had 900 feet of line out for a while and the camera was well out of the clearing were it could see the tree tops as I never had.

Sunrise Orchards

We looked into the sun a lot that day.

At midday on Sunday. With a north wind, we looked into the sun a lot that day.

There was good sun and enough wind to loft a camera on both Saturday and Sunday last weekend, and the apples were just starting to bloom. So I knocked on Barney Hodges’ back door and introduced myself. Barney bought a 200 acre dairy farm in 1974 and started planting apple trees. His son runs Sunrise Orchards now, and Barney seems quite content to be in his beautiful old farmhouse in Cornwall surrounded by thousands of apple trees that he planted. He graciously permitted me to fly a kite and take photos, and I did.

Lemon Fair

Grass fire along the Lemon Fair River, April 18, 2012. Photo by Preston Turner.

Grass fire along the Lemon Fair River, April 18, 2012. Photo by Preston Turner.

I thought I had finally done everything right. The Flowform 16 was flying steadily in a 15 mph breeze (with gusts to 20) and easily lofting the full KAP rig with Canon S95. My plan was to take vertical photos for combining into an orthophoto image of a hayfield that had been partly burned two days earlier by the farmer. Preston had posted some dramatic photos of the evening blaze advancing across the field, and the burn pattern looked impressive when I drove by the next day looking for way to get closer to it. On my return a day later, I avoided asking permission for farm road access, and just parked two miles away and walked along the Lemon Fair River. Because the good wind provided plenty of lift, I opted for the full KAP rig and radio control instead of just the camera pointed down and shooting every ten seconds. That gave me the option of also taking some oblique shots, and the 5:00 PM shadows of burr oaks and silver maples were already enticing on the new grass. Radio control also allowed me to release the shutter only when the rig was quiet between sways, and to take far fewer photos than the ten second intervalometer would have taken.

Test Flight

Ever since I backed the balloon mapping Kickstarter project, I have been thinking about what to do with the matched pair of visible and infra-red cameras I will receive next month. I’m intrigued by the idea of making NDVI images by combining information from the two cameras. NDVI maps of vegetation can reveal new ecological patterns, but I still have no idea what I might learn with this tool. I have also been thinking about how to deploy the cameras to take aerial photos. The level of my Kickstarter pledge entitles me to a kit with cameras and other things, but it is not yet clear what other things will be included. So when it was 50° a couple of weeks ago and tolerable to work in the garage, I started playing with a piece of one of the aluminum storm window frames that were thrown behind the shed. The goal was to make a cheap, lightweight, self-leveling rig to hold two cameras pointing in the same direction: down.

NOrtho Photo

Aspen seedlings and fireweed in a burned study plot.

While in Alaska in June I visited some mountain treeline study plots we established in 1998 to describe and monitor the population of white spruce at the transition between subalpine forest and alpine tundra. I searched the plots for new spruce seedlings and remeasured the ones that had been previously located and marked. A wildfire burned through some of the plots in 2004, and a new tree species has since established where the organic soil was consumed. Thousands of seedlings of quaking aspen now grow in the plots, and I recorded their number and height in subplots. These are healthy seedlings growing in the tundra where, prior to 2004, the only trees were a few stunted spruce. This invasion will be either a short-lived experiment that ends when the aspens try to grow taller than the winter snowpack, or the start of a novel treeline community. Monitoring these plots will eventually reveal how this plays out, so in the meantime counting and measuring a few things is considered to be science.

Photosynth Thesis

A couple of weeks ago I took some photos and video from the KAP rig lofted on the Flow Form 16 kite above a clearing behind the house. I did not get far stitching the images into a panorama, and had to move on to other business. Since then I have used Photosynth, which will not only display stitched panoramas, but the multiple unstitched overlapping images. The photos do not need to be taken from the same place, so KAP images should be well suited. Photosynth will create and display a 3D model of the surfaces in the photographs. The model consists of the points that Photosynth has determined are shared in two or more photos, and the 3D plot of those points based on photogrammetric analysis of the images. You can toggle a display of the point cloud in the Photosynth viewer below.

Built to fly

I awoke this morning to see that not a leaf on the hornbeam was fluttering, and my head fell back to the pillow in dismay.  This was a sure sign that I had a new hobby.  It was the KAPer’s lament: no wind. I had flown a camera on a kite for two days in a row, and the thought of a calm day was discouraging.  But I had started a stitch of yesterday’s aerial panorama before I went to bed, so I got up two hours before Galen had to be at school to check on it.

All the parts before assembly

All the parts before assembly

I built my first KAP rig last week from one of Brooks Leffler’s kits. I have never built anything with servos and dip switches and carbon fiber legs, but I got to use my Dremel tool, so it felt safe.  Brooks has designed an elegant system for suspending a camera so that it can point in any direction.  The pointing and shutter release are done either at predetermined intervals (autoKAP), or by radio control from the ground.  The kit I built had servo motors for both panning and tilting and electronics to automatically point in as many as 76 directions and take photos potentially covering a downward-looking half-spherical view. By replacing the tiny circuit board with a radio receiver, the motors and shutter could be controlled via a transmitter on the ground.  It is based on the RC airplane/car/boat/helo standards, so compatible equipment is readily available.

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