i think youre right
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i think youre right
ive prob been around longer than u queers
:projecting:Quote:
Originally Posted by hiroshima
can macs get haunted by ghosts that make fun of Heroes for you?
nope? looks like alienware wins again
alienwares have high specs but their hardware is low quality crap that's why you can spend $8000 and end up with a machine that bluescreens all the time
Basic Principles of Photogrammetry
What is photogrammetry?
The science and technology of obtaining spatial measurements and other geometrically reliable derived products from photographs
Measurements include distances, areas, elevations to generate digital elevation models (DEM’s), orthophotos, thematic GIS data, ect.
Digital and softcopy refer to any photogrammetric operation involving the use of digital raster photographic image data.
Historic use of photogrammetry has been the production of topographic maps
Basic Geometric Characteristics of Aerial Photographs
Considered either vertical or oblique
-Vertical photographs are made with the camera axis directed as vertically as possible (perpendicular) to the ground
-True vertical rare to obtain due to angular rotations, or tilts, caused by the angular attitude of the aircraft at time of exposure
-Vertical aerial photographs have been between 1 and 3 degrees of tilt.
-Oblique area photographs are taken with intentional tilt
-High oblique aerial photographs contain the horizon
-Low oblique aerial photographs do not.
Taking Vertical Aerial Photographs
-The photographs are usually taken along a series of parallel passes called flight strips or flights lines
-The line traced on the ground beneath the aircraft is called the nadir line
-Connects the image centers of the vertical photographs
-This lapping along the flight line is called end lap
-The area of coverage common to an adjacent pair of photographs in a flight line is called the stereoscopic overlap area.
-The pair of photos is called a stereopair
-The amount of end lap is normally between 55 and 65 %
-Need at least 50% endlap for stereoscoptic coverage
Figure 3.1
-The ground distance between photo centers at the time of exposure is called the air base
-Vertical exaggeration is the ratio of air base to flying height
-The larger the base-height (BH) ratio, the greater the vertical exaggeration.
-Adjacent flights lines are photographed so that there is also a lateral overlapping of adjacent strips called side lap
-Normally held at approximately 30%
-The photographs of two or more sidelapping strips used to cover an area is referred to as a block of photos
-A block of photos can be “cut and passed” together to create a photo mosaic over the project area.
Figure 3.3.4
Geometric Elements of a Vertical Photograph
Photocoordinate measurement can be made from a variety of devices
Can use:
-An engineers scale for low orders of measurements accuracy
-Coordinate digitizer table
-A comparator
Photocoordinates can be in “page units” or “image units”
Errors in photocoordinate measurements include:
-Failure of fiducial axes to intersect at the principal point
-Shrinkage or expansion of photographic materials
-Lens distortions
-Atmospheric refraction distortions
-Earth curvature distortions
SCALES
Photographic scale is like map scale
-The scale of a photograph is the ratio of a distance on the photo to that same distance on the ground.
-On a map, scale is uniform everywhere because a map is an orthographic projection.
-An aerial photograph, on the other hand, is a perspective projection and, as will be demonstrated herein, its scale varies with variations in terrain elevation.
Scales may be expressed as:
-Unit equivalent
-Representative fractions, or
-As a ratio
For example, 1 cm on a map or photo represents 100 m (10 000cm) on the ground, the scale expressed in the aforementioned three ways is:
-Unit equivalent 1 cm = 100m
-Representative fractions, or 1 / 10,000
-As a ratio 1:10,000
Large scale vs. small scale
-1:10,000 vs. 1:50,000 which is larger?
-1: 10,000 is larger.
Scale over flat terrain
-Can calculate scale by measuring the corresponding photo and ground distances between two points
-Points must be identifiable on both the photo and ground, thus:
Scale = Photo distance (d) or (ab)/ground distance (D) or (AB)
Scale is also a function of focal length (f) of the camera used to acquire the image and the flying height above ground, (H’)
-Scale=camera focal length (f)/flying height above terrain (H’)
OR
-Scale=camera focal length (f)/flying height at datum (H) –elevation above datum (h)
Example 3.1
-Assume that two road intersections shown on a photograph can be located on a 1:25,000 scale topographical map. The measured distance between the intersections is 47.2 mm on the map and 94.3 mm on the photograph. What is the scale of the photograph? At that scale what is the length of the fence line that measure 42.9 mm on the photograph?
find ground distance
1 mm on the map= 25,000 mm on the ground
1mm on the map= 25 m on the ground (times each side by 47.2)
Ground Distance = 1,180 m
Scale=Photo distance (d) or (ab)/ground distance (D) or (AB)
= 94.3(0,0943)/1,180
Ans:12,500
Example 3.2
-A camera equipped with a 152 mm focal length lens is used to take a vertical photograph from a flying height of 2780m above mean sea level. If the terrain is flat and located at an elevation of 500m, what is the ground scale of the photograph?
Ans: 15,000
Example 3.3
-Assume that a vertical photograph was taken at a flying height of 5,000m above sea level using a camera with a 152 mm focal lens. Determine the photo scale at points A and B,which lie at elevations of 1200 and 1960 m. What ground distance corresponds to a 20.1 mm photo distance measured at each of these elevations?
Ans (1200): 25,000
Ans (1960): 20,000
-For the 20.1 multiply each answer by 0.201 and you’ll get your ground distance.
The average scale for an entire photograph is based on the average terrain elevation for the area imaged.
-Savg=f/H-havg
-The result of the photo scale variation is geometric distortion
-All points on a map are depicted at their true relative horizontal (planimetric) positions
-Photo locations taken over varying terrain are displaced from their true map positions
-The difference in position of geometric distortion results from a map being scaled in an orthographic projection whereas a vertical aerial photograph yields a perspective projection
i dont want to hear it
my pass is whatdidyousay, try it out
ok but if i log in with my vpn you can't see my ip from recently logged in if that's what you are trying to do you genius
Q: Does a wigger who sucks nigger dick?
A: Hiroshima
Q: Does a wigger who lick nigger anus?
A: Juji
~*~ what is, elz ~*~
Quote:
Originally Posted by elezzzark
who is juji i dont even know what you are talking about
hiroshima is hacking the sitie
:projecting:Quote:
Originally Posted by hiroshima
Clay told me was barryQuote:
Originally Posted by Gentleman Doli
...............barrys had it with his real name being posted on the forums
..............its time........ for The Revenge of Tim™
What does he demand here before to hack this forum?Quote:
Originally Posted by rubycalaber
his only demands are that we suffer
Tim's Vengeance knows no mercy
What did this forum to Tim?
posting his real name too much, we have to refer to him now as Tim Who Must Not Be Named lest we incur his ungodly wrath
Filter his real name before is too late
it is already too late for those who oppose Tim Who Must Not Be Named
Tim arbeu
tims hole lol/
Timothy arbeu of new south wales australia?Quote:
Originally Posted by elezzzark
hey I just noticed the font in the reply box changed, weird
our fonts are now under the control of Big Boy Barry
hes already starting to take our g and any letter could be next
curse you fools who have invoked the wrath of The Dastardly Dunro
huh for some reason the g is normal when its on its own niggersniggers fuckingniggers
g
nigger
my mortal mind cannot comprehend the full scope of Tim's Tricks™
Tim's Tricks™
timothy arbeu of new south wales, australia sent pictures of his erect penis and buttocks to an underage girl
The opening scene of the first Mad Max is like the best beginning scene for a movie ever
I AM THE NIGHT RIDER!!!!!! THE TOE CUTTER, HE KNOWS WHO I AM!!! IIIIIII AAAAAM THE CHOSEN ONE!!!!