python 调用gdal读取tiff 遥感大图像。

因为遥感图像都是tiff格式，而且分辨率大，一张图都有几十G，opencv搞不定，只能用gdal。之前搞了半天，稀里糊涂的把gdal装上去了，都忘记怎么装的，到处都是坑。

怕忘记怎么用，参考：http://www.dengb.com/Pythonjc/1318700.html

def readTif(fileName):
	
	merge_img = 0
	driver = gdal.GetDriverByName('GTiff')
	driver.Register()
 
	dataset = gdal.Open(fileName)
	if dataset == None:
		print(fileName+ "掩膜失败，文件无法打开")
		return
	im_width = dataset.RasterXSize #栅格矩阵的列数
	print('im_width:', im_width) 
 
	im_height = dataset.RasterYSize #栅格矩阵的行数
	print('im_height:', im_height) 
	im_bands = dataset.RasterCount #波段数
	im_geotrans = dataset.GetGeoTransform()#获取仿射矩阵信息
	im_proj = dataset.GetProjection()#获取投影信息
	
 
	if im_bands == 1:
		band = dataset.GetRasterBand(1)
		im_data = dataset.ReadAsArray(0,0,im_width,im_height) #获取数据
		cdata = im_data.astype(np.uint8)
		merge_img = cv2.merge([cdata,cdata,cdata])
 
		cv2.imwrite('C:/Users/summer/Desktop/a.jpg', merge_img)
# 
	elif im_bands == 4:
	# 	# im_data = dataset.ReadAsArray(0,0,im_width,im_height)#获取数据
	# 	# im_blueBand = im_data[0,0:im_width,0:im_height] #获取蓝波段
	# 	# im_greenBand = im_data[1,0:im_width,0:im_height] #获取绿波段
	# 	# im_redBand = im_data[2,0:im_width,0:im_height] #获取红波段
	# 	# # im_nirBand = im_data[3,0:im_width,0:im_height] #获取近红外波段
	# 	# merge_img=cv2.merge([im_redBand,im_greenBand,im_blueBand])
 
	# 	# zeros = np.zeros([im_height,im_width],dtype = "uint8")
 
	# 	# data1 = im_redBand.ReadAsArray
 
	# 	band1=dataset.GetRasterBand(1)
	# 	band2=dataset.GetRasterBand(2)
	# 	band3=dataset.GetRasterBand(3)
	# 	band4=dataset.GetRasterBand(4)
	
		data1=band1.ReadAsArray(0,0,im_width,im_height).astype(np.uint16) #r #获取数据
		data2=band2.ReadAsArray(0,0,im_width,im_height).astype(np.uint16) #g #获取数据
		data3=band3.ReadAsArray(0,0,im_width,im_height).astype(np.uint16) #b #获取数据
		data4=band4.ReadAsArray(0,0,im_width,im_height).astype(np.uint16) #R #获取数据
	# 	print(data1[1][45])
	# 	output1= cv2.convertScaleAbs(data1, alpha=(255.0/65535.0))
	# 	print(output1[1][45])
	# 	output2= cv2.convertScaleAbs(data2, alpha=(255.0/65535.0))
	# 	output3= cv2.convertScaleAbs(data3, alpha=(255.0/65535.0))
 
		merge_img1 = cv2.merge([output3,output2,output1]) #B G R
		
		cv2.imwrite('C:/Users/summer/Desktop/merge_img1.jpg', merge_img1)