Good morning,

I'm working with PNG files, and the metadata is stored in two separate files: .pgw and .png.aux.xml. Currently I'm forced to use the same name for the three files, i.e. the image and the two auxiliary files with the geographical information. This is cumbersome and inconvenient, because I have a set of images that share the same georeferentiation and currently I'm forced to clone the .pgw and .png.aux.xml files in a somewhat silly way for introducing each image. Is there a way to tell rasterio.open that the two files with the metadata are named different from the PNG image?

Thanks a lot!

I have been flying some drone surveys over the ocean and need to properly project and georeference and warp my images. I have all the information I think I need: lat, lon, altitude, yaw, pitch, and roll along with sensor optics params. I have to imagine this can be done with some existing package and I had thought some rasterio functions were suitable, but I can't find any. So I've been using the cameratransform package to get the GPS positions of the corners of my image to feed into rasterio:

 

import cameratransform as ct

 

# camera parameters

 

cam = ct.Camera(ct.RectilinearProjection(focallength_mm=f,

                                         sensor=sensor_size,

                                         image=image_size),

               ct.SpatialOrientation(elevation_m=img.altitude,

                                     tilt_deg=pitch+sensor_offset,

                                     roll_deg=roll,

                                    heading_deg=yaw))

 

# gps pts are lat lon

cam.setGPSpos(img.latitude, img.longitude, img.altitude)

 

# these are the coordinates of the image corners

coords = np.array([cam.gpsFromImage([0 , 0]), \

    cam.gpsFromImage([image_size[0]-1 , 0]), \

    cam.gpsFromImage([image_size[0]-1, image_size[1]-1]), \

    cam.gpsFromImage([0 , image_size[1]-1])])

From there I'm not certain what to do. I've tried basically saying these corners are GCPs and trying to warp the image in rasterio:

 

import rasterio

 

gcp1 = rasterio.control.GroundControlPoint(row=0, col=0, x=coords[0,1], y=coords[0,0], z=coords[0,2], id=None, info=None)

gcp2 = rasterio.control.GroundControlPoint(row=image_size[0]-1, col=0, x=coords[1,1], y=coords[1,0], z=coords[1,2], id=None, info=None)

gcp3 = rasterio.control.GroundControlPoint(row=image_size[0]-1, col=image_size[1]-1, x=coords[2,1], y=coords[2,0], z=coords[2,2], id=None, info=None)

gcp4 = rasterio.control.GroundControlPoint(row=0, col=image_size[1]-1, x=coords[3,1], y=coords[3,0], z=coords[3,2], id=None, info=None)

 

# Register GDAL format drivers and configuration options with a

# context manager.

with rasterio.Env():

    

    # open the original image to get some of the basic metadata

    with rasterio.open(path_name, 'r') as src:

        profile = src.profile

                    

    # create rasterio transform

    tsfm = rasterio.transform.from_gcps([gcp1,gcp2,gcp3,gcp4])

    

    # I also tried this function but to no avail

    #tsfm = rasterio.warp.calculate_default_transform(rasterio.crs.CRS({"init": "epsg:4326"}), rasterio.crs.CRS({"init": "epsg:4326"}), img.size()[0], img.size()[1], gcps=[gcp1,gcp2,gcp3,gcp4])

 

    crs = rasterio.crs.CRS({"init": "epsg:4326"})

 

    profile.update(

        dtype=rasterio.uint8,

        transform = tsfm,

        crs=crs)

        

    with rasterio.open('example.tif', 'w', **profile) as dst:

        dst.write(src.read().astype(rasterio.uint8), 1)

This does produce an image but it is not properly warped. It is just in the correct location. Since my sensor is a 40 deg off nadir the warping should be reasonably significant, when I warp it with cameratransform's cam.getTopViewOfImage() function I get this:

So I'm curious if I'm missing some rasterio function or ability, isn't what the GCPs should be doing in the transform.from_gcps() function?

Is it expected that during reading process rasterio doesn't take into account rotation angle for rotated rasters (transform has non-zero rotation) ? In order to make it works properly I had to do gdalwarp.

Same question for the "show" method. It just draws array as it is without considering the rotation angle.