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Grid Cell Counting
- determining surface area of a feature
- method 1: count the whole and partial of map area. Whole + partial/2= # cells. # cells * grid cell area m2= # in m2 = ##.# hectares
- method 2: grid cells sq* # of grid cells = grid cell # in2 ; grid cell # * RF2= #in2; #in2 / 144 in2/ft2 = #sq feet
- [determining surface area of a feature]
- count dots inside lake and black dots on edge, measure grid cells with dots and convert and divide by 4. Total dots * grid per dot area = #m2 = # hectares.
- [determining surface area of a feature]
- equally spaced parallel lines that define narrow strips across the features. Construct perpendicular lines that define the edges of the feature with the strips. Measure the length of the strips and sum them. Multiply total strip length with strip width.
- [determining surface area of a feature]
- Tracing the edges with the lens and trading points. Tool.
Coordinate Methods using a coordinate system
Coordinate Methodsusing a coordinate system of (x1,y1). Area = (x1 +x2)*(y1+y2)....
give each column and row numbers. Then with in the those rows and columns count how many cells are being used of that area, and sum. Then multiply cells by that row or column number and sum, this is the product. Take the sum of product/by the sum of cells, this gives your x and y coordinates.
- [volume of a feature]
- given elevation, randomly place points within that contour lines.
- Give the elevations of those points estimate the average and then subtract from base elevation to obtain average height.
Slab Summation Method
- dissecting the elevations a slab at a time. Take the middle measure frothe base then multiply be the difference of the top slab by the bottom. The top slab is in a shape of a cone with a volume of 1/3π*R2h.
- H = cone height, πR2 = area of circular base.
- [volume of a feature]
- taking the shape and consturcting a circle with that shape using itscentroid. Shape = 1.0 [ overlap of circle and shape/ area of both]
- Compactness: A x 4π / p2
- compactness of shape often is desirable, because most efficiently serviced and defended.
- Indexes are based on area and parameter.
- Slope: vertical change in the land surface.
- Rise/Run: y/x; elevation difference (rise) and ground distance (run), taking two points higher – lower/ ground distance.
- Slope angle: degrees, tan-1(y/x)
- Slope percentage: y/x * 100
- maximum slope at a point on a surface.
- Vectors: magnitude and directions.
gives differentcolors for different compass directions as well as degrees.
Finding constant slope paths
perpendicular to the contour lines, this is the steepest downhill route.
mapping out thecontour lines on a line graph
visibility may be showincorrectly when a vertically exaggerated profile is used in aprofile.
- use frames. Cameras located in air planes. Before during the war pigeons, 1957 -U2 and now we have the SR-71 blackbird.
- Black and white: panchromatic (all colors); shorter blue wavelengths scatter by atmosphere reduces clarity causing photo to look hazy. [forests, topographic, road building, recreation]
- True-color: emulsion layers blue, green and red. [vegetation, soils, geologic mapping, surface water studies]
- Color-Infrared: world war II, CIR film, sensitive to IR and visible light.healthy vegetation = higher the IR.
devices collect images of reflected or emitted energy from small portions of electromagnetic spectrum (spectrum bands). Short to long waves [visible light, near- infrared(IR), thermal-infrared (TIR), and microwave bands.]
Side looking airborne radar: (SLAR)
antenna to emit pulses of microwave energy (1-30 cm) and then measure the energy reflected back from landscape. Strength of returned signal converted to gray tones. Advantages: not dependent on external energy, all weather, day or night. Bright spot = specular reflector, smooth right angle.
most detailed, ground surface – 1,500 feet about ground. Small ground area at a large map scale.
less environmental detail, 1,500-10,000 feet.
10-20 miles,U2 & SR-71, larger ground area covered
record thermal-infraredenergy we sense as heat, no dependence on reflected visible light. Detect [ water pollution from power plants, industries using watercooling purposes, potential geothermal energy areas, edges of forestfires, boundaries of ocean currents, underground streams.] buildings giving off heat
point directly under the camera, near the ground surface
Conjugate Principal Points (CPP)
location of the principal point on the first photo located and plotted as a point on the second photo.
Digital Elevation Model
- A sample of elevations or depths taken on a regular grid. Sometimes called digital terrain model (DTM)World
- wide coverage - SRTM, ETOPO and GlobeUS
- coverage - National Elevation Dataset
Shuttle Imaging Radar (SIR):
L bandside looking radar. Black and white to highlight terrain, faults,folds, drainage patterns.
Light Detection and Ranging (LIDAR)
- Simply making lots of accurate distance measurements with a laser rangefinder.
- Accurate laser rangefinders are commonly used as surveying instruments, measuring tapes, rifle scopes, even golf aids!
- Distance is calculated by measuring the time that a laser pulse takes to travel to and from an object
- Each laser pulse can produce multiple consecutive measurements from reflection off several surfaces in its path.
- National Aerial Photography Program
- Photo Id Number
- Photo Acquisition Date
Determining Map Scale from Reference Material
- ((1/x)/(1/msd)) = pd/msd
- x = msd *md/pd
Describe methods of calculating RF of an aerial photograph
- method 1: 1/x =f/H > x = H/f ..H: flying height, f: focal point
- Ex. x=H/f=(10,000 ft x 12in/ft)/6in = 20,000
- method 2: x= (alt.-elev.)/f
- Ex. x= ((10,000ft -2,000ft)x12in/ft)/6 in=16,000
- method 3: 1/x = measured length or width/ standard length or width
- method 4: x=msdxmd/pdex: same 2 road .3 in on photo & .6 in on 1:24,000 scalex = 24,000 x .6 in/.3 in = 48,000
Radial Displacement Method
- height of object (ho) = Hd/r
- d= length of displaced object
- r=radial distance from principal point
- H=aircraft flying height
Shadow Method of Height Determination
- ho/So = hx/Sx
- hx = unknown feature height
- Sx = shadow length of unknown feature
- ho = known feature height
- So = shadow length of known feature
- h=Hdp / (P +dp)
- Define: apparent displacement of objects when viewed from the perspective of different vantage points
- = b1+b2 or (P1 +P2)
- b1:the base of object to the principal point
- b2: the base of object to the principal point
- P1: principal point to the other principal point
- P2: principal point to the other principal point
- = (T1 -b1) + (T2-b2)
- T1: top far corner of object to principal point
- T2: top far corner of object to principal point
- b1: the base of object to the principal point
- b2 :the base of object to the principal point
Feature Identification elements:
shape, tone, color, size, height, shadow, pattern, texture, and site/situation.
- most fundamental identification clue.
- Decide if a shape is likely of natural or human origin.
- Natural : irregular shapes
- Human: simple geometric forms (straight sides, sharp angles, smooth curves)
- object's lightness or darkness on the image.
- tonal differences create contrasts which are fundamental to feature detection and identification.
- B/W: amount of visible light reflect to camera
- Reflectors: mirror (specular), diffuse (lambertian), corner
- Thermal: amount of radiant thermal energy detected by sensor [thermal capacity (amount of energy it can store), conductivity (resistance to heating or cooling), inertia (rate at which it gains or loses heat)]
- On side-looking RADAR images: amount of backscatter to antenna
- dominant wavelengths of visible spectral energy received by our eye.
- hue: spectral aspect of the phenomenon
- saturation: brightness or intensity
- potential problem images are available at a variety of scales.
- Object size estimation.
- relative heights of features may be crucial to your identification of their function and their setting.
- relative position: object located on the side of a tall feature. (feature identification)
- cast by environmental features are important image interpretation cues.
- conifers: cone shape
- Deciduous: oval shape
- Repetition of certain spatial forms or relationships is characteristic of many environmental features.
- Signal underlying process.
- Represents order which has a cause.
- individuals together have a shape, size, arrangement, shadow, and tone to create a pattern of tonal variation.
- Range from coarse to fine.
- Smaller and smaller = finer = disappear.
Site and Situation
- Relation of an object to surrounding features can provide useful hints to its identity, and may be only way to recognize some objects.
- Situation: means of anticipating what to look for on a image.
Gentle slope, spaced out evenly
Steep, close together, rapid
Concave,closely spaced at the top of the hill, with progressive widening, U shaped
Conves, widely spaced at the top and closely spaced down the hill
- vertical, overlay, ticks point towards the bottom
- a: valley; long and narrow area with a v-shaped
- b: ravine; deep narrow steep sided valley formed by water erosion
- two higher elevation hills between is a dip
Major Landforms Types
- Dissected Plateau
- Uniformly sloping plain
- Ridge and valley topography
- Braided River channel
- Alluvial fan
- Karst Topography
- Alpine Glaciation
- Continental Glaciation
- radial drainage
- pattern of ever smaller, roughly circular, concentric contours that end at the summit.
- Slopes: uniformly steep from summit to lower elevations
- Snowfields near the summit are visible
- Radial pattern of roughly straight ski runs as cuts through the forests
- Radial Drainage
- straight streams that radiate outward from the summit
- consistent with volcanoes
- Drift less area subject to continental glaciation, remnant of dissected plateau
- Covered by gently sloping valleys, steep ridges, gently sloping ridge tops
- V-shaped contours outlining valleys and ravines
- Dendritic drainage pattern
- dissected plateaus
- soft sedimentary rocks (shale) erode in a Dendritic manner
- Shaped like a leaf, and the streams look like veins
- Ridge tops resistant to erosion (sandstone/limestone)
Uniformly Sloping Plain
- Parallel Drainage
- equally spaced contours (zigzag form) runs diagonally across map
- V's are perpendicualr to contour
- Parallel drainage pattern
- pronounced uniform slope
- Small tributary gullies form perpendicular to main stream
- Elongated landforms, by lava eruptions .
Ridge and Valley
- trellis drainage
- ridges and valleys, ancient mountain ridges
- continents collided
- Trellis drainage pattern
- ridge and valley
- synclines (down turned folds), form long, straight, narrow valleys in which major streams flow
- Small tributary streams run straight down the sides of the up turned parallel ridges (anticlines) and join the main stream at right angles.
- watergaps: main stream eroded through ridges
- tectonic activity beneath crust bowed the rock layers upward into an ellipse shaped
- Annual Drainage
- Cuestas: smooth ridges
- Hogback: steeper serrated ridges
- Annular Drainage
- streams flow parallel to valleys between cuestas and hogbacks then breaks into right angles
- Shallow depression in the middle
- Playa lakes form in middle
- Meandering Drainage
- Flat valleys, meandering rivers , cutoff meanders, oxbow lakes. Meander scars river cuts a curve into higher ground.
- Meandering Drainage Pattern
Braided River Channel
- tributary streams bring in more sediment than the main channel.
- Long periods of low stream flow interspersed with short periods of high stream flows.
- Alpine /polarareas drained by season, glacial meltwater streams.
- Deposition of sand and gravel, broad shallow channel.
- several channels merge and subdivide repeatedly
- Sand and gravel bars
- small islands
- streams carrying high sediment loads from mountains to flat valleys
- Intense rainstorms
- evenly spaced semi circular contour lines, uniform, gently sloping conical landforms
- fan drainage
- edge of the valley
- steam resembling a rib of a the fan
- landscape largely shaped by dissolving action of water on carbonate bedrock (limestone, dolomite or marble)
- rainwater pics up carbon dioxide from the air and dead plant, percolates, dissolving rocks
- Interrupted Drainage
- Disappearing streams
- Springs or natural wells
- Disappearing strams
- sinkhole lakes
- karst topography
- Dendrictic Drainage
- Pleistocene Period
- tarn lakes
- col (saddles)
- Disrupted Drainage
- ice sheets advanced and retreated
- small kettles
- Disrupted Drainage
- numerous lakes
- small kettles
- marsh areas
- : Period, Formation
- oldest to youngest
- Normal Fault
- line with circle = HW
- Thrust Fault
- line with triangles = HW
- gives the magnitude or angle of rocks tilt
- as well as what direction
- shows the values of serveral types of surface observations taken at hourly intervals for major meteorological stations across the country.
- cold and warm fronts, temperature zones, low and high pressure centers
- National Doppler Radar Maps
- Wind Velocity Maps
- average monthly and yearly atmosphere condition's.
- Data collect: precipitation and temperatures averages
- Digital elevation models data are input into a computer PRISM model.
- Average Annual Precipitation
- Monthly Climate Maps
- Koppean System
Species Distribution Maps
- Plant Specimen and observation maps: habitat, climate, landform, ecoregions
- Individual animal maps: movement, GPS transmitters
- Migratory Route Maps: birds fly patterns
species range maps
- region of inhabit of species
- spotted owl's.
township survey maps
- early 1850's, rich source of information on initial settlement of an area.
- historic settlement pattern
- within cities often reflects people adjustment to physical, admin., economic, and cultural.
- county planning department show this inventory. Parcels
- current land use
housing pattern, divided into zoning districts, residential , commercial, industrial and open space.
- patterns of rural landcover at different scales with different levels of details.
- categories: urban, ag., forested and water.
- Crops grown location, and methods
- study of socioeconomic groups that differ in gender, age, race, ethnicity, income or occupation.
- maps show different socioeconomic groups reside.
- Census tracts generally have between 1,500 and 8,000 people, with an optimum size of 4,000 peopleAlso, county, zip code, and blocks, a subdivision of tracks