Convert x,y position to LLA in decimal degree

Question

I am trying to convert a pixel position (x,y) on a map tile to Longitude, Latitude, Altitude (LLA) format (decimal degree). I have a piece of a map from google earth over Spain at night time. I have the LLA for all four corners and I want know the LLA location of a pixel at x:657, y: 81

How do I know which map projection to use? Is there an easy way to calculate the LLA position for each pixel in this image? and can the same method be applied to different map tiles from google earth?

I am trying to develop this conversion either on python or matlab

Thanks

Asked By: Sami Arja

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Source

Answer 1

I am sure there is a much better solution, I am pretty new to python, but this is how I would start looking at approaching it if I were looking for a longitude and latitude at a given pixel position. *My apologies if that is not exactly what you are looking for, I may have misunderstood.

# image size in pixels
img_size = [807, 152]

# Pixel position
px_pos = (225, 35)

def calc_lla(top_r_lat, top_r_long, bottom_l_lat, bottom_l_long, map_size, pos):

  # Taking the latitude of the upper right corner and bottom left, subtracting them, dividing the difference by map size in pixels, then multiplying that with the position given
  lat = top_r_lat - (((top_r_lat - bottom_l_lat) / map_size[0]) * pos[0])

  # same as above for longitude
  long = top_r_long - (((top_r_long - bottom_l_long) / map_size[1]) * pos[1])
  return (lat, long)


print(calc_lla(44.372321, -7.904955, 40.801188, -3.088944, img_size, px_pos))

# Returns (43.37665194795539, -6.79600509868421)

Answered By: Jason Lewis

Answer 2

Since you’re getting your image out of Google Earth, you should be able to get the lat/lon/alt right there in Google Earth. Just hover your mouse over the image at the location you want, and read the values out of the status bar.

Answered By: C.A.

Convert x,y position to LLA in decimal degree

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