I have 5 numpy arrays of shape nx, ny
lons.shape = (nx,ny) lats.shape = (nx,ny) reds.shape = (nx,ny) greens.shape = (nx,ny) blues.shape = (nx,ny)
My question is how do I write this data to a geotiff?
I ultimately want to plot the image using basemap.
Here is the code I have so far, however I get a huge GeoTIFF file (~500MB) and it comes up blank (just a black image). Also note that nx, ny = 8120, 5416.
from osgeo import gdal from osgeo import osr import numpy as np import h5py import os os.environ['GDAL_DATA'] = "/Users/andyprata/Library/Enthought/Canopy_64bit/User/share/gdal" # read in data input_path = '/Users/andyprata/Desktop/modisRGB/' with h5py.File(input_path+'red.h5', "r") as f: red = f['red'].value lon = f['lons'].value lat = f['lats'].value with h5py.File(input_path+'green.h5', "r") as f: green = f['green'].value with h5py.File(input_path+'blue.h5', "r") as f: blue = f['blue'].value # convert rgbs to uint8 r = red.astype('uint8') g = green.astype('uint8') b = blue.astype('uint8') # set geotransform nx = red.shape[0] ny = red.shape[1] xmin, ymin, xmax, ymax = [lon.min(), lat.min(), lon.max(), lat.max()] xres = (xmax - xmin) / float(nx) yres = (ymax - ymin) / float(ny) geotransform = (xmin, xres, 0, ymax, 0, -yres) # create the 3-band raster file dst_ds = gdal.GetDriverByName('GTiff').Create('myGeoTIFF.tif', ny, nx, 3, gdal.GDT_Float32) dst_ds.SetGeoTransform(geotransform) # specify coords srs = osr.SpatialReference() # establish encoding srs.ImportFromEPSG(3857) # WGS84 lat/long dst_ds.SetProjection(srs.ExportToWkt()) # export coords to file dst_ds.GetRasterBand(1).WriteArray(r) # write r-band to the raster dst_ds.GetRasterBand(2).WriteArray(g) # write g-band to the raster dst_ds.GetRasterBand(3).WriteArray(b) # write b-band to the raster dst_ds.FlushCache() # write to disk dst_ds = None # save, close
I think the issue is when you create the Dataset, you pass it GDT_Float32. For standard images with pixel ranges 0-255, you need GDT_Byte. Float requires values to be between 0-1 typically.
I took your code and randomly generated some data so I could test the rest of your API. I then created some dummy coordinates around Lake Tahoe.
Here is the code.
#!/usr/bin/env python from osgeo import gdal from osgeo import osr import numpy as np import os, sys # Initialize the Image Size image_size = (400,400) # Choose some Geographic Transform (Around Lake Tahoe) lat = [39,38.5] lon = [-120,-119.5] # Create Each Channel r_pixels = np.zeros((image_size), dtype=np.uint8) g_pixels = np.zeros((image_size), dtype=np.uint8) b_pixels = np.zeros((image_size), dtype=np.uint8) # Set the Pixel Data (Create some boxes) for x in range(0,image_size[0]): for y in range(0,image_size[1]): if x < image_size[0]/2 and y < image_size[1]/2: r_pixels[y,x] = 255 elif x >= image_size[0]/2 and y < image_size[1]/2: g_pixels[y,x] = 255 elif x < image_size[0]/2 and y >= image_size[1]/2: b_pixels[y,x] = 255 else: r_pixels[y,x] = 255 g_pixels[y,x] = 255 b_pixels[y,x] = 255 # set geotransform nx = image_size[0] ny = image_size[1] xmin, ymin, xmax, ymax = [min(lon), min(lat), max(lon), max(lat)] xres = (xmax - xmin) / float(nx) yres = (ymax - ymin) / float(ny) geotransform = (xmin, xres, 0, ymax, 0, -yres) # create the 3-band raster file dst_ds = gdal.GetDriverByName('GTiff').Create('myGeoTIFF.tif', ny, nx, 3, gdal.GDT_Byte) dst_ds.SetGeoTransform(geotransform) # specify coords srs = osr.SpatialReference() # establish encoding srs.ImportFromEPSG(3857) # WGS84 lat/long dst_ds.SetProjection(srs.ExportToWkt()) # export coords to file dst_ds.GetRasterBand(1).WriteArray(r_pixels) # write r-band to the raster dst_ds.GetRasterBand(2).WriteArray(g_pixels) # write g-band to the raster dst_ds.GetRasterBand(3).WriteArray(b_pixels) # write b-band to the raster dst_ds.FlushCache() # write to disk dst_ds = None
Here is the output. (Note: The goal is to produce colors, not terrain!)
Here is the image in QGIS, validating the projection.
