NaN according to whether average constraint is > 0.5. If used with -T 2 the output will be average data value or With -T 3 it will report an average constraint between 0 andġ. Squares, and create one output pixel for each such square. N navg Average the values in the input img pixels into navg by navg C to set coordinates relative to projection center. Written in the grid header remark, so it can be found later. Sphere, the user can make overlays with the adjusted -R so that Of the image, measured in user default units, with -Jm1 and The grid file header is set so that the xĪnd y axis lengths represent distance from the west and south edges Slightly the modified region corresponds to the edges of pixels [or Preserved, so that the region -R set by the user is modified
The Spherical Mercator projection of the img file is M Output a Spherical Mercator grid [Default is a geographic lon/lat Not usually required since we canĭetermine the pixel size from inspection of the size. I Indicate inc as the width of an input img pixel in minutes of This case the region set by -R must be given in multiples of the Grid must match the requested region and have x_inc = y_inc. Small interpolation errors and should only be used if the output Range, and furthermore the grid increment in latitude does not match By default, theįinal region is a direct projection of the original Mercator regionĪnd will typically extend slightly beyond the requested latitude The exact same region as requested with -R. E Can be used when -M is not set to force the final grid to have Not usually required since we canĭetermine the extent from inspection of the file size. Alternatively,Īppend minlat/maxlat as the latitude extent of the input img file. Optional Arguments ¶ -C Set the x and y Mercator coordinates relative to projection center In the latter case a perspective view of the plane is This needs to beĭone only when using the -Jz option, not when using only the In case of perspective view ( -p), a z-range ( zmin, zmax)Ĭan be appended to indicate the third dimension. To determine actual rectangular geographic region.įor perspective view ( -p), optionally append / zmin/ zmax. Appending +u unit expects projected (Cartesian)Ĭoordinates compatible with chosen -J and we inversely project R settings (and grid spacing, if applicable) are copied from I is used to create the corresponding region.Īlternatively, specify the name of an existing grid file and the Refers to, and the grid dimensions nx and ny with grid spacings via Indicates which point on a rectangular region the lon/ lat coordinate
#Extract img file code#
Īlternatively for grid creation, give R code lon/ lat/ nx/ ny, whereĬode is a 2-character combination of L, C, R (for left, center, or right)Īnd T, M, B for top, middle, or bottom. Outward by adding these increments instead. Alternatively, use +R to extend the region Use +r to modify the bounding box coordinates from the polygon(s):Īppend inc, xinc/ yinc, or winc/ einc/ sinc/ ninc to adjust the NA (North America), or SA (South America). Whole continent, prepend = to any of the continent codes AF (Africa),ĪN (Antarctica), AS (Asia), EU (Europe), OC (Oceania), R code1,code2.] instead:Īppend one or more comma-separated countries using the 2-character
#Extract img file iso#
Set geographic regions by specifying ISO country codes from the Digital Chart of the World using Two shorthands -Rg and -Rd stand for global domain (0/360Īnd -180/+180 in longitude respectively, with -90/+90 in latitude). R west/ east/ south/ north west, east, south, and north specify the region of interest,Īnd you may specify them in decimal degrees or inĪnd upper right map coordinates are given instead of w/e/s/n. G grdfile grdfile is the name of the output grid file. $GMT_DATADIR else it will try to open imgfile directly. $GMT_DATADIR, then img2grd will try to find imgfile in If the user has set an environment variable Topography fields estimated from satellite altimeter data by Required Arguments ¶ imgfile A Mercator img format file such as the marine gravity or seafloor