copters and lasers map grand canyon - laser measuring instrument

by:UMeasure     2019-10-21
copters and lasers map grand canyon  -  laser measuring instrument
Written by john noble wilfordjuly 1972, this is a digital version of an article from The Times Print Archive, which was published online in 1996.
To keep these articles as they appear initially, the Times will not change, edit, or update them.
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The arritz Grand Canyon. —
In The Great Canyon, the silence of a mile and 2 billion years is full of edges, and a bright new sun appears in a flash on the southern horizon.
The dark orange ball flashed, and then fired a line of light at the target 10 miles away? ? ? .
For those who come to the Grand Canyon to look for and meditate, it must be a confusing signal that more visual stimuli are dealt with by the mind that has been overwhelmed by the grandeur of ubiquity.
For those few who come to the canyon to measure and map, it is a reassuring sign that they want to narrow the Canyon down to a scale that is more easily understood by humans.
Laser is working.
Advertising says the Sun-neon light beam from the edge to the edge, reflected through a quartz prism, returns to its source in a way that provides the most accurate measurement of the Grand Canyon's history.
For the past two years, the canyon has been looking for a new portrait, the first truly massive map of 100 square miles in the center of the National Park.
According to the doctor, the results in a few years
The 62-year-old explorer Bradford Washburn
The cartographer in charge of the Boston Museum of Science will publish a map depicting the most visited parts of the canyon in a ratio of 3 inch to 1 mile.
The map is now one-inch to one-mile, with a pencil dot covering 50 feet.
"No matter how good, you can't plan and execute such hiking or horseback riding on the inch-to-a-mile map," Dr.
Washburn says more than 2 million visitors visit the Canyon each year, and thousands of them venture deep into the canyon.
In addition, the "manuscript" on which the finished map is based will be drawn in a ratio of 1 feet to 1 mile.
These are valuable for botanists, geologists, archaeologists, and others who do research in the canyon.
Under the guidance of Dr, for those engaged in small surveying and mapping adventures, this is an exciting labor of loveWashburn.
The Boston Museum of Science and the National Geographic Society supported the program in collaboration with the National Park administration, but many of the dozens of participants volunteered for free.
Drawing places like the Grand Canyon, there are steep cliffs and sharp rocky spires, there are blurry trails and lofty promontories, "says Dr. ," It's like drawing an upside down
His experience included making the first map of Mount McKinley.
In the most recent week of the current phase of the Canyon Project, the fourth expedition since the beginning of mapping, Dr.
Washburn's party set up a surveying and mapping station on the spires that have never been climbed, took a helicopter into the remote side canyon, painted the trails and measured the distance with a laser.
All of this is an important area of work for map makers to build mathematical frameworks that enable them to transform aerial photography into accurate maps.
In fact, the first step of the project is aerial photography.
On a Celtic day in July 1970, a plane with a six-inch camera flew over the canyon at a speed of 16,000 feet, scanning the terrain vertically and horizontally.
Previous aerial photos were taken at 35,000 feet, so less detail was shown.
After processing the picture, each strip covers three strips with a wide mileage, and the map painter enters the "get control ".
"That is, they have to determine the elevation and distance of the known points in the canyon.
All the other content in the photo and final map will be related to these 42 selected points.
The strategy for selecting control points is simple.
Pick some along the South Rim, on the south side of the Colorado River, pick more in the canyon, pick more along the north side of the river, and pick more along the north edge.
The four lines are roughly parallel.
To cross check the accuracy of the measurements, each station must be clearly visible from no less than three other stations.
"In mapping, you have to start somewhere and we chose Yaki Point," Dr. explained . "
Washburn stands on the Cape, one of the most popular tourist lookout on the south edge.
The brass benchmark was implanted there, which was established a long time ago by the US Geological Survey and the US coast and surveyors.
This is already a known point"
Its latitude and longitude are accurately calculated at an altitude of 7,260 feet.
"If you don't have that 'knowledge'," said Dr.
Washburn said, "You have to build them by looking at the stars to determine where you are. Dr. advertising
Washburn then placed a tripod on the benchmark, placing the wild T-3 photoelectric sensor directly on it.
He put down a string with a lead hammer so that it fell right at the center Dent of the marker pen.
"This part of the mapping is very routine," he said, as he squinted at the 40-fold telescope of the photoelectric telescope and focused on one of the control points in the canyon.
"But it pays off on accuracy.
Sometimes you do more than a dozen sightings at the same point to check for errors.
"1 inch three miles away, the 40-pound instrument, is a modern version of the old-fashioned surveyor's transit, which focuses the cross line of the telescope on the target point, then it refers to a closed glass, etching all the angles of the compass on it.
With a modern station, it is possible to determine the angle of accuracy to a tenth of a second.
Three miles away, a second. That's it, doctor.
Washburn can accurately determine the distance from any point above or below another point, as well as the horizontal angle.
But there may be complications.
In the hot weather, warm air rushes to the edge of the canyon like an invisible waterfall, which may distort the view of the Jingyi, making the object like a mirage on the highway
The best time to visit is early morning or close to sunset.
Tourists will also encounter obstacles.
Once, at the burn point, doctor.
Washburn saw him on Angel's corner and said loudly, "Oh, for God's sake, there is a tourist sitting in front of that thing!
"In addition to a control point, the target at all control points is either a piece of glass, or a glowing orange color painted by metal, and then screwed into the pine tree drilled at the precise target point, or draw a similar Little Earth so it can be seen in any direction.
The helicopter ran several times in order to measure with a laser.
During the first trip, Wendell Mason, a member of Harry R Boston researchFeldman, Inc.
, Fly over the canyon to Angel point, highlighting the northern edge of the Grand Canyon Lodge.
Place the prism in the PlaceAt Point and need to remove the orange metal target and screw in the screws in a set of seven quartz prism.
They can accept light from different angles and reflect it back to the light source.
As soon as the mirror is in place, the advertisement begins.
Mason informed.
Washburn, at the Yavapai Point on the south edge, via two-way radio. Then B. Q.
The laser operator "Buddy" carshaw focused on the reflector and turned on the glare beam.
The man-made Sun passes through the canyon.
This laser device, known as Rangemaster, is manufactured by laser systems and electronics companies.
Tula horma, Tennessee.
, The same principle as the laser used in the Apollo program to more accurately determine the distance between the Earth and the moon.
Similar devices are increasingly used in earth measurements.
This is done by the so-called "phase comparison. ” Mr.
Cut shaw is seen on the reflector by the built-in Questar telescope of the laser instrument mounted on the tripod.
Then he directed the laser.
The first letter of acronym that reflects radiation stimulation on prihms to emit light amplification.
When the reflected beam returns, it is converted to an electrical signal.
A small computer built into the instrument is programmed to correct the distortion of light reflection and the curvature of the Earth.
It "knows" the speed of light.
It has a timer.
Therefore, it reaches the distance between two points by measuring the time required for the beam to travel back and forth.
A dull click, a moment of waiting, then a few Amber numbers appear on the panel behind the instrument.
"The surveyor used to be happy with the error factor of Part 1 of 5,000, about 1 feet per mile," said Mr.
Carshaw, product manager at laser.
"Our accuracy in this thing is one in a million.
"Angel point stands on a boulder on the edge of the cliff, with a bit of a dazzling feeling, and it is not recommended for anyone who is prone to fear of heights.
First glance over the edge, straight down a few thousand feet, a moment of dizziness can overcome the callow mapper.
Once this feeling has passed, recall John Wesley Powell --
In 1869, he was the first person to explore the length of the Grand Canyon and gave it a name --
Frankly, it took a few years to "calm my nerves down so that I could sit down and get my feet over the edge and calmly look down at the 2,000 feet-meter cliff.
The Grand Canyon is 277 miles long, 1 mile deep and 18 miles wide.
The laminated walls of purple, dark red, gray and cream tell about the ancient oceans, deserts, rivers and disasters 2 billion years ago.
This inspired the Russian poet Yevtushenko to describe the canyon as "the womb of the times from the inside out ".
One day, the map carvers overheard a little girl asking her mother, "Mom, what did they do with everything they dug out of here ? "?
The Colorado River knows the answer.
Over the past few million years, the canyon has been formed by volcanic, seismic and glacial-melting floods, but mainly by the steady grinding and cutting of Colorado's rapid water flow.
This is also a natural coincidence: the fact that the elevation of the land creates the surrounding plateau matches the erosion capacity of the river.
If the speed of the rise is faster, the river changes direction, which usually happens.
From the Angel, sir.
Mason flew down from Guangming Angel Canyon by helicopter and passed through some ancient cliff dwellings to another place near the ribbon waterfall.
The site is so hidden that it is necessary to burn the torch in order for the gentleman to be able to use it
Cutshaw aimed at the laser.
The map team returned to the south on one more stop, returning to the south edge.
But for a few minutes of anxiety, the helicopter did not seem to match the stiff sinking air flow in the canyon.
The wind blows from the southern edge to a few hundred feet at the bottom of the canyon.
The helicopter could not break through the wind.
"You can lose the height of 2,000 feet like this," said pilot Marion "rag" conconway, clapping his finger.
"It puts you on your seat belt.
However, the problem from the bottom is that the elevation rises, not the loss of the elevation. Mr.
Connaught, a 24-year-old Vietnam helicopter flight veteran, moves toward the north wall of the canyon.
Usually, after the wind weakens near the bottom, it enters the butter and rises.
But not this time.
Next, he flew to the Canyon in Colorado, hoping that the larger heat there would generate some rise. Again, no luck.
Finally, advertising.
Connaught flew as close as possible to the south wall, about 100 feet metres, and found enough updraft between the wall and downdraft to enable the helicopter to struggle up and down the canyon. By then, Dr.
Washburn is already recording new data and drawing the distance on the photo.
Surprisingly, he says, how close the new data is to the old map of the canyon.
Francois Matthes made the first complete Canyon map for geological survey in 1902.
His party went with mules and feet, not by helicopter.
They can't get to many buttons in the canyon, but they draw them by doing a triangle measurement from a known baseline.
They use steel tape measure that can be transported by rail, not laser and Sky meter.
"When a person works in this magnificent but dry, dizzying wilderness," Dr.
Bradford commented, "respect for these elderly people has never stopped rising.
"In 1960, geological surveys remapped the area using aerial photography.
There is still a lot of work to be done, and there is a lot of work to be done before the new massive canyon map is ready.
Rockwood mapping is using all the pictures and data
Rochester tracks the outline on the "manuscript" map.
The work should be completed by October.
It will then go back to the scene and sketch in Trails, buildings and other details that are not always fully visible in aerial photos.
Started on a hike along the cable trail from the south edge.
Everyone in the party turns to push the surveyor's measuring wheel.
Its circumference is 5.
28 feet, so every full turn of the wheel will click a mile on the meter.
When a mule train carrying tourists passed by, a woman was amused by the sight of a presumably rational man pushing the wheel down the path.
"What are you doing," she asked with a smile. "ride a wheelbarrow to the bottom?
"Advertise on a steep cliff, doctor.
Washburn pointed out that this will bring a terrible problem to the cartographer who must prepare the finished map.
"It's very steep if you have a 70 degree slope, but you can still describe it," Dr.
Washburn explained.
"But if it is 90 degrees, vertical like this, there is no space on the map to draw any symbols, because the bottom of the cliff is exactly the same as the top, only 1,000 feet below
We have to come up with some way of shadow reliefs.
The Swiss are good at this.
"Dehydration is a danger at the foot of the Red Wall, one of the most unique layers of the canyon wall, 0. 335 billion years ago, limestone oozes from the bottom of the sea, the map carvers rest in the shade of Boulder, I drank grapefruit juice.
Dehydration is one of the biggest dangers in the canyon, where, at temperatures above 100 degrees Fahrenheit, it can be an oven for dry air.
Hikers may lose a lot of important moisture without realizing it, as the sweat evaporates into the thirsty air immediately.
At the end of the difficult hike, the reward is the unparalleled joy brought by the tired, satisfied body of the Bright Angel Creek's torrent cooling and massage Map Maker.
On a trip to the Donto trail, the helicopter landed on a sunburned red rock below the peak of Dana Bart.
It is said that there are many places in the canyon where, in the words of the old explorer, human hands have never set foot --
Dana Bart has so far been considered one of those untouched places.
From the landing site, it was a 6 feet-long climb that crossed the thick red sand sheet and reached a peak about wide, eroded at the top of a more durable limestone base.
There, a surveying and mapping station was implanted with the possibility of looking down at the dazzling drop of 2,000 feet and looking up at the southern edge of the Pima Point to see tourist spots.
A man stands there alone and realizes the sound of silence.
It's the soft roar of the wind, the mumbling molecules, that's all.
Elsewhere, map carvers sometimes hear the whoosh sound of a diving swallow, which may have been angered by the invasion.
In an advertisement for Dana Butte, an island in space, one can understand some of the inexpressible feelings Neil Armstrong experienced at the moon's tranquil base. Dr.
Washburn said he could foresee one day, perhaps not far from remote sensing instruments, and that photography and computing would be so fine that accurate maps could be made without any field work.
This will bring a lot of hard work and boredom to the mapping.
But it also takes away the satisfaction of future map carvers standing in places like Dana Bart, a benchmark of time, loneliness and beauty.
A version of this file was printed on page 39 of the New York edition on July 19, 1972 with the title: Copters and Lasers map Grand Canyon.
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