old algorithm ran in O(a*b*c) time, where a is the number of points in
the LIDAR file, b and c are the dimentions of the resulting heatmap. new algorithm runs in O(a) time... before, it took ~5 days on my machine to make a 1000*1000 heatmap. now it takes 5 seconds to make ANY size image. (the graph making library takes a bit longer, but it is very little compared to mapping the image array.)
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1 changed files with 46 additions and 74 deletions
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@ -12,110 +12,82 @@ import seaborn as sns; sns.set_theme()
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import matplotlib.pyplot as plt
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from PIL import Image
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logging.basicConfig(format='%(asctime)s:%(levelname)s:%(message)s', level=logging.INFO)
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logging.basicConfig(format='%(asctime)s:%(message)s', level=logging.INFO)
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#logging.basicConfig(format='%(asctime)s:%(message)s', level=logging.DEBUG)
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def sort(array):
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#sort by zDim column, first to last.
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logging.debug(f'zDim sliced points is\n{array[:,zDim]}')
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#the [::-1] reverses the resulting array, so that sortedPoints will be from biggest to smallest.
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ind = np.argsort(array[:,zDim])[::-1]
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sortedPoints = array[ind]
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logging.debug(f'sortedPoints is\n{sortedPoints}')
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return sortedPoints
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def scale(array, desiredmaxX, desiredmaxY):
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logging.debug(f'xMax is {np.max(array[:,xDim])} and xMin is {np.min(array[:,xDim])}')
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logging.debug(f'yMax is {np.max(array[:,yDim])} and yMin is {np.min(array[:,yDim])}')
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ax=desiredmaxX/(np.max(array[:,xDim])-np.min(array[:,xDim]))
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bx=-ax*np.min(array[:,xDim])
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ay=desiredmaxY/(np.max(array[:,yDim])-np.min(array[:,yDim]))
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by=-ay*np.min(array[:,yDim])
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def scale(array, xRange, yRange, maxX, maxY):
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logging.debug(f'xRange is {xRange} and yRange is {yRange}')
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xScale = maxX/xRange
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yScale = maxY/yRange
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scaledArray = sortedPoints[:, 0:3]
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scaledArray[:,xDim]=scaledArray[:,xDim]-mins[xDim]
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scaledArray[:,xDim]=scaledArray[:,xDim]*xScale
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logging.debug(f'xmin in scaledArray is {scaledArray[:,xDim].min()}')
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logging.debug(f'xmin in scaledArray is {scaledArray[:,xDim].max()}')
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#slice indexes 0-2 from the second dimention
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array[:,xDim]=ax*array[:,xDim]+bx
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array[:,yDim]=ay*array[:,yDim]+by
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scaledArray[:,yDim]=scaledArray[:,yDim]-mins[yDim]
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scaledArray[:,yDim]=scaledArray[:,yDim]*yScale
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logging.debug(f'ymin in scaledArray is {scaledArray[:,yDim].min()}')
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logging.debug(f'ymin in scaledArray is {scaledArray[:,yDim].max()}')
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logging.debug(f'scaledArray is\n{scaledArray}')
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return scaledArray
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logging.debug(f'array is\n{array}')
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logging.debug(f'xMax is {np.max(array[:,xDim])} and xMin is {np.min(array[:,xDim])}')
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logging.debug(f'yMax is {np.max(array[:,yDim])} and yMin is {np.min(array[:,yDim])}')
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def isInxyRange(xMin, xMax, yMin, yMax, xVal, yVal):
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return (xMin<=xVal) and (xVal<xMax) and (yMin<=yVal) and (yVal<yMax)
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return array
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imgX=1000
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imgY=1000
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imgX=500
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imgY=500
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#TODO: make it iterate over multiple files.
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inFile = os.path.realpath(sys.argv[1])
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lasFile = laspy.file.File(inFile, mode = "r")
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lasFile = laspy.file.File(inFile, mode = 'r')
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outFile = f'{os.path.dirname(inFile)}/{imgX}*{imgY}{os.path.basename(inFile)}.png'
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print(f'outputing to {outFile}')
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#import each dimention scaled.
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z = lasFile.z
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x = lasFile.x
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y = lasFile.y
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z = lasFile.z
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maxes = np.array(lasFile.header.max)*np.array(lasFile.header.scale)
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mins = np.array(lasFile.header.min)*np.array(lasFile.header.scale)
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logging.debug(f'max values is {maxes}')
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logging.debug(f'min values is {mins}')
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intensity = lasFile.intensity
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#dimention that will be z(top down) dimention in final heatmap. TODO: auto detect this based on dimention with least variance.
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zDim=0
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xDim=1
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yDim=2
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points = np.stack((z,x,y), axis=-1)
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#dimention that will be z(top down) dimention in final heatmap. TODO: auto detect this based on dimention with least variance.
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zDim=1
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xDim=2
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yDim=0
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points = np.stack((x,y,z,intensity), axis=-1)
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#points should now look like
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#[[x,y,z,intensity]
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# [x,y,z,intensity]
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#[[z,x,y]
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# [z,x,y]
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# ...
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# [x,y,z,intensity]
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# [x,y,z,intensity]]
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# [z,x,y]
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# [z,x,y]]
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logging.debug(f'points is\n{points}')
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print(f'{points.shape[0]} points in LIDAR file.')
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#found experimentally.
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print(f'estimated worst-case time is {points.shape[0]*7.77e-07*imgX*imgY} sec')
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xRange = maxes[xDim]-mins[xDim]
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yRange = maxes[yDim]-mins[yDim]
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zRange = maxes[zDim]-mins[zDim]
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sortedPoints = sort(points)
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length=points.shape[0]
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print(f'{length} points in LIDAR file.')
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imageArray = np.zeros((imgX, imgY))
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scaledArray = scale(points, xRange, yRange, imgX, imgY)
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points = scale(points, imgX, imgY)
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for x in range(imgX):
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for y in range(imgY):
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if x==imgX:
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xMax=x+2
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else:
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xMax=x+1
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if y==imgY:
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yMax=y+2
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else:
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yMax=y+1
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zVal=0
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logging.debug(f'yMax is {yMax} and xMax is {xMax}')
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for i in range(scaledArray.shape[0]):
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if isInxyRange(x, xMax, y, yMax, scaledArray[i,xDim], scaledArray[i,yDim]):
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zVal = scaledArray[i,zDim]
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break;
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imageArray[x,y]=zVal
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print(f'zVal at {x},{y} is {zVal}')
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#sys.exit()
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#for each entry in points, figure out what pixel it will go into, and assign that pixel the zval, unless the zval already in that pixel is higher.
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for i in range(len(points)):
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print(f'{i} points processed of {length} total points')
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#the if statements are reqired for edge cases relateing to the bottom row and the far right column, to make sure points dont get left out.
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xPixel=np.floor(points[i,xDim]).astype(int)
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if xPixel==imgX:
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xPixel-=1
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yPixel=np.floor(points[i,yDim]).astype(int)
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if yPixel==imgY:
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yPixel-=1
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imageArray[xPixel,yPixel]=np.maximum(imageArray[xPixel,yPixel], points[i,zDim])
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logging.debug(f'imageArray is {imageArray}')
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heatMap = sns.heatmap(imageArray, center=((maxes[zDim]+mins[zDim])/2), square=True)
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heatMap = sns.heatmap(imageArray, center=(np.max(imageArray)+np.min(imageArray))/2, robust=True, square=True)
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heatMapFig = heatMap.get_figure()
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heatMapFig.savefig(outFile)
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