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Usage. Outputs from the Solar Radiation Graphics tool are raster representations and are not maps that correspond to the outputs from the area or point solar radiation analysis. Rather, they are representations of directions in a hemisphere of directions looking upward from a given location. In a hemispherical projection, the center is the zenith, the edge of the circular 'map' is the horizon, and the angle relative to the zenith is proportionate to the radius. Hemispherical projections do not have a geographic coordinate system and have a bottom left corner of (0,0).
It would not be practical to store viewsheds for all locations in a DEM, so when input locations are not specified, a single viewshed is created for the center of the input surface raster. When input point features or locations file are specified, multiple viewshed rasters are created for each input location. When multiple locations are specified, the default output format is an ESRI GRID stack, which contains multiple bands that correspond to the viewshed for each location.
The input locations table can be an INFO table, a.dbf file, an Access table, or a text file. Output graphic display rasters do not honor extent or cell size environment settings. The output extents are always respective of the sky size/resolution and have a cell size equal to one. However, the underlying analysis will use the environment settings and may affect the results of the viewshed. One or two sunmap rasters may be generated, depending on whether the time configuration includes overlapping sun positions throughout the year. When two sunmaps are created, one represents the period between the winter and summer solstice (December 22 to June 22), and the other represents the period between the summer solstice and the winter solstice (June 22 to December 22).
Solar Radiation Tool
When multiple sunmaps are created, the default output is an ESRI GRID stack. When the output is added to ArcMap, only the first band will be displayed. The latitude for the site area (units: decimal degree, positive for the north hemisphere and negative for the south hemisphere) is used in calculations such as solar declination and solar position. The analysis is designed only for local landscape scales, so it is generally acceptable to use one latitude value for the whole DEM. With larger datasets (i.e., states, countries, or continents), the insolation results will differ significantly at different latitudes (greater than 1 degree). To analyze broader geographic regions, it is necessary to divide the study area into zones with different latitudes.
For input surface rasters containing a spatial reference, the mean latitude is automatically calculated; otherwise, the latitude will default to 45 degrees. When using an input layer, the spatial reference of the data frame is used. Sky size is the resolution of the viewshed, sky map, and sun map rasters which are used in the radiation calculations (units: cells per side). These are upward-looking, hemispherical raster representations of the sky and do not have a geographic coordinate system. These grids are square (equal number of rows and columns). Increasing the sky size increases calculation accuracy but also increases calculation time considerably. When the 'day interval' setting is small (e.g., 14 days).
A sky size value of 512 is sufficient for calculations at point locations where calculation time is less of an issue. At smaller day intervals (e.g. # Name: SolarRadiationGraphicsEx02.py # Description: Derives raster representations of a hemispherical viewshed, # sunmap, and skymap, which are used in the calculation of direct, diffuse, # and global solar radiation. Motomidman v0 70. # Requirements: Spatial Analyst Extension # Import system modules import arcpy from arcpy import env from arcpy.sa import. # Set environment settings env.
Workspace = 'C:/sapyexamples/data' # Set local variables inRaster = 'elevation' pntFC = 'observers.shp' skySize = 200 zOffset = 2 directions = 32 latitude = 52 timeConfig = TimeMultipleDays ( 2009, 91, 212 ) dayInterval = 14 hourInterval = 0.5 outSunMap = 'c:/sapyexamples/output/sunmap' zenDivisions = 8 aziDivisions = 8 outSkyMap = 'c:/sapyexamples/output/skymap' # Check out the ArcGIS Spatial Analyst extension license arcpy. CheckOutExtension ( 'Spatial' ) # Execute SolarRadiationGraphics outViewshedMap = SolarRadiationGraphics ( inRaster, pntFC, skySize, zOffset, directions, latitude, timeConfig, dayInterval, hourInterval, outSunMap, zenDivisions, aziDivisions, outSkyMap ) # Save the output outViewshedMap. Save ( 'c:/sapyexamples/output/viewmap' ).
. Available with Spatial Analyst license. The solar radiation analysis tools calculate insolation across a landscape or for specific locations, based on methods from the hemispherical viewshed algorithm developed by Rich et al. (Rich 1990, Rich et al. 1994) and further developed by Fu and Rich (2000, 2002).
The total amount of radiation calculated for a particular location or area is given as global radiation. The calculation of direct, diffuse, and global insolation are repeated for each feature location or every location on the topographic surface, producing insolation maps for an entire geographic area. Solar radiation equations Global radiation calculation Global radiation ( Global tot) is calculated as the sum of direct ( Dir tot) and diffuse ( Dif tot) radiation of all sun map and sky map sectors, respectively. Global tot = Dir tot + Dif tot Direct solar radiation Total direct insolation ( Dir tot) for a given location is the sum of the direct insolation ( Dir θ,α) from all sun map sectors: Dir tot = Σ Dir θ,α (1) The direct insolation from the sun map sector ( Dir θ,α) with a centroid at zenith angle ( θ) and azimuth angle ( α) is calculated using the following equation: Dir θ,α = S Const. β m(θ). SunDur θ,α. SunGap θ,α.
cos(AngIn θ,α) (2). where:.
S Const — The solar flux outside the atmosphere at the mean earth-sun distance, known as solar constant. The solar constant used in the analysis is 1367 W/m 2.
This is consistent with the World Radiation Center (WRC) solar constant. β — The transmissivity of the atmosphere (averaged over all wavelengths) for the shortest path (in the direction of the zenith). m(θ) — The relative optical path length, measured as a proportion relative to the zenith path length (see equation 3 below). SunDur θ,α — The time duration represented by the sky sector. For most sectors, it is equal to the day interval (for example, a month) multiplied by the hour interval (for example, a half hour).
For partial sectors (near the horizon), the duration is calculated using spherical geometry. SunGap θ,α — The gap fraction for the sun map sector. AngIn θ,α — The angle of incidence between the centroid of the sky sector and the axis normal to the surface (see equation 4 below). Relative optical length, m(θ), is determined by the solar zenith angle and elevation above sea level. For zenith angles less than 80°, it can be calculated using the following equation: m(θ) = EXP(-0.000118.
Elev - 1.638.10 -9. Elev 2) / cos(θ) (3). where:. θ — The solar zenith angle.
Elev — The elevation above sea level in meters. The effect of surface orientation is taken into account by multiplying by the cosine of the angle of incidence. Angle of incidence ( AngInSky θ,α) between the intercepting surface and a given sky sector with a centroid at zenith angle and azimuth angle is calculated using the following equation: AngIn θ,α = acos( Cos(θ). Cos(G z) + Sin(θ). Sin(G z). Cos(α-G a) ) (4).
where:. G z — The surface zenith angle. Note that for zenith angles greater than 80°, refraction is important.
G a — The surface azimuth angle. Anime romance game. Diffuse radiation calculation For each sky sector, the diffuse radiation at its centroid ( Dif) is calculated, integrated over the time interval, and corrected by the gap fraction and angle of incidence using the following equation: Dif θ,α = R glb.
P dif. Dur. SkyGap θ,α. Weight θ,α.
cos(AngIn θ,α) (5). where:.
R glb — The global normal radiation (see equation 6 below). P dif — The proportion of global normal radiation flux that is diffused. Typically it is approximately 0.2 for very clear sky conditions and 0.7 for very cloudy sky conditions. Dur — The time interval for analysis. SkyGap θ,α — The gap fraction (proportion of visible sky) for the sky sector. Weight θ,α — The proportion of diffuse radiation originating in a given sky sector relative to all sectors (see equations 7 and 8 below).
AngIn θ,α — The angle of incidence between the centroid of the sky sector and the intercepting surface. The global normal radiation ( R glb) can be calculated by summing the direct radiation from every sector (including obstructed sectors) without correction for angle of incidence, then correcting for proportion of direct radiation, which equals 1-P dif: R glb = (S Const Σ(β m(θ))) / (1 - P dif) (6) For the uniform sky diffuse model, Weight θ,α is calculated as follows: Weight θ,α = (cosθ 2- cosθ 1) / Div azi (7). where:. θ 1 and θ 2 — The bounding zenith angles of the sky sector. Div azi — The number of azimuthal divisions in the sky map. For the standard overcast sky model, Weight θ,α is calculated as follows: Weight θ,α = (2cosθ 2 + cos2θ 2 - 2cosθ 1 - cos2θ 1) / 4.
Div azi (8) Total diffuse solar radiation for the location ( Dif tot) is calculated as the sum of the diffuse solar radiation ( Dif) from all the sky map sectors: Dif tot = Σ Dif θ,α (9) References Fu, P. A Geometric Solar Radiation Model with Applications in Landscape Ecology. Thesis, Department of Geography, University of Kansas, Lawrence, Kansas, USA.
Fu, P., and P. The Solar Analyst 1.0 Manual. Helios Environmental Modeling Institute (HEMI), USA. Fu, P., and P. 'A Geometric Solar Radiation Model with Applications in Agriculture and Forestry.' Computers and Electronics in Agriculture 37:25–35.
Hetrick, and S. 'Using Viewshed Models to Calculate Intercepted Solar Radiation: Applications in Ecology. American Society for Photogrammetry and Remote Sensing Technical Papers, 524–529.
'Topoclimatic Habitat Models.' Proceedings of the Fourth International Conference on Integrating GIS and Environmental Modeling. Related topics.
Usage. Outputs from the Solar Radiation Graphics tool are raster representations and are not maps that correspond to the outputs from the area or point solar radiation analysis. Rather, they are representations of directions in a hemisphere of directions looking upward from a given location.
In a hemispherical projection, the center is the zenith, the edge of the circular 'map' is the horizon, and the angle relative to the zenith is proportionate to the radius. Hemispherical projections do not have a geographic coordinate system and have a bottom left corner of (0,0). It would not be practical to store viewsheds for all locations in a DEM, so when input locations are not specified, a single viewshed is created for the center of the input surface raster. When input point features or locations file are specified, multiple viewshed rasters are created for each input location. When multiple locations are specified, the default output format is an ESRI GRID stack, which contains multiple bands that correspond to the viewshed for each location. Gta 4 crack download. The input locations table can be an INFO table, a.dbf file, an Access table, or a text file.
Output graphic display rasters do not honor extent or cell size environment settings. The output extents are always respective of the sky size/resolution and have a cell size equal to one. However, the underlying analysis will use the environment settings and may affect the results of the viewshed. One or two sunmap rasters may be generated, depending on whether the time configuration includes overlapping sun positions throughout the year.
When two sunmaps are created, one represents the period between the winter and summer solstice (December 22 to June 22), and the other represents the period between the summer solstice and the winter solstice (June 22 to December 22). When multiple sunmaps are created, the default output is an ESRI GRID stack. When the output is added to ArcMap, only the first band will be displayed.
The latitude for the site area (units: decimal degree, positive for the north hemisphere and negative for the south hemisphere) is used in calculations such as solar declination and solar position. The analysis is designed only for local landscape scales, so it is generally acceptable to use one latitude value for the whole DEM. With larger datasets (i.e., states, countries, or continents), the insolation results will differ significantly at different latitudes (greater than 1 degree). To analyze broader geographic regions, it is necessary to divide the study area into zones with different latitudes. For input surface rasters containing a spatial reference, the mean latitude is automatically calculated; otherwise, the latitude will default to 45 degrees.
When using an input layer, the spatial reference of the data frame is used. Sky size is the resolution of the viewshed, sky map, and sun map rasters which are used in the radiation calculations (units: cells per side).
These are upward-looking, hemispherical raster representations of the sky and do not have a geographic coordinate system. These grids are square (equal number of rows and columns). Increasing the sky size increases calculation accuracy but also increases calculation time considerably.
When the 'day interval' setting is small (e.g., 14 days). A sky size value of 512 is sufficient for calculations at point locations where calculation time is less of an issue. At smaller day intervals (e.g. # Name: SolarRadiationGraphicsEx02.py # Description: Derives raster representations of a hemispherical viewshed, # sunmap, and skymap, which are used in the calculation of direct, diffuse, # and global solar radiation. # Requirements: Spatial Analyst Extension # Import system modules import arcpy from arcpy import env from arcpy.sa import. # Set environment settings env. Workspace = 'C:/sapyexamples/data' # Set local variables inRaster = 'elevation' pntFC = 'observers.shp' skySize = 200 zOffset = 2 directions = 32 latitude = 52 timeConfig = TimeMultipleDays ( 2009, 91, 212 ) dayInterval = 14 hourInterval = 0.5 outSunMap = 'c:/sapyexamples/output/sunmap' zenDivisions = 8 aziDivisions = 8 outSkyMap = 'c:/sapyexamples/output/skymap' # Check out the ArcGIS Spatial Analyst extension license arcpy.
CheckOutExtension ( 'Spatial' ) # Execute SolarRadiationGraphics outViewshedMap = SolarRadiationGraphics ( inRaster, pntFC, skySize, zOffset, directions, latitude, timeConfig, dayInterval, hourInterval, outSunMap, zenDivisions, aziDivisions, outSkyMap ) # Save the output outViewshedMap. Save ( 'c:/sapyexamples/output/viewmap' ).
Usage. Outputs from the Solar Radiation Graphics tool are raster representations and are not maps that correspond to the outputs from the area or point solar radiation analysis. Rather, they are representations of directions in a hemisphere of directions looking upward from a given location. In a hemispherical projection, the center is the zenith, the edge of the circular map representation is the horizon, and the angle relative to the zenith is proportionate to the radius. Hemispherical projections do not have a geographic coordinate system and have a lower left corner of (0,0).
It would not be practical to store viewsheds for all locations in a DEM, so when input locations are not specified, a single viewshed is created for the center of the input surface raster. When input point features or locations files are specified, multiple viewshed rasters are created for each input location. When multiple locations are specified, the output will be a multiband raster, where each band corresponds to the viewshed for a specific location. The input locations table can be a point feature class or a table of point coordinates. When inputting locations by table, a list of locations must be specified with an x,y coordinate. The table can be a geodatabase table, a.dbf file, an INFO table, or a text table file.
If using an ASCII coordinate file, each line should contain an x,y pair separated by a comma, space, or tab. Output graphic display rasters do not honor extent or cell size environment settings. The output extents are always respective of the sky size/resolution and have a cell size equal to one.
However, the underlying analysis will use the environment settings and may affect the results of the viewshed. One or two sun map rasters may be generated, depending on whether the time configuration includes overlapping sun positions throughout the year. When two sun maps are created, one represents the period between the winter and summer solstice, and the other represents the period between the summer solstice and the winter solstice. Depending on the year, the solistices typically fall on the 20th or 21st of December and June, but occasionally they may be on the 22nd. When multiple sun maps are created, the default output is a multiband raster. The latitude for the site area (units: decimal degree, positive for the northern hemisphere and negative for the southern hemisphere) is used in calculations such as solar declination and solar position.
The analysis is designed only for local landscape scales, so it is generally acceptable to use one latitude value for the whole DEM. With larger datasets, such as for states, countries, or continents, the insolation results will differ significantly at different latitudes (greater than 1 degree). To analyze broader geographic regions, it is necessary to divide the study area into zones with different latitudes. For input surface rasters containing a spatial reference, the mean latitude is automatically calculated; otherwise, the latitude will default to 45 degrees.
When using an input layer, the spatial reference of the data frame is used. Sky size is the resolution of the viewshed, sky map, and sun map rasters that are used in the radiation calculations (units: cells per side). These are upward-looking, hemispherical raster representations of the sky and do not have a geographic coordinate system. These rasters are square (equal number of rows and columns). Increasing the sky size increases calculation accuracy but also increases calculation time considerably. When the day interval setting is small (for example, 14 days).
A sky size value of 512 is sufficient for calculations at point locations where calculation time is less of an issue. At smaller day intervals (for example.
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# Name: SolarRadiationGraphicsEx02.py # Description: Derives raster representations of a hemispherical viewshed, # sunmap, and skymap, which are used in the calculation of direct, diffuse, # and global solar radiation.