CLOUD DETECTION AND REMOVAL TECHNIQUES FOR LANDSAT 8 IMAGERYWITH GPU ACCELERATION 2016 / B10209047 /

INTRODUCTION

Abstract

Cloud Detection and Removal Techniques for Landsat 8 ImageryPrevious WorkNvidia CUDA

CPUGPU

VS

Previous Workhttp://wiki.theoutpost.io/files/remote-sensing/hallahan-prepperneau-geo544-final-abstract.pdf

http://wiki.theoutpost.io/files/remote-sensing/hallahan-prepperneau-geo544-final-abstract.pdfhttp://wiki.theoutpost.io/files/remote-sensing/hallahan-prepperneau-geo544-final-abstract.pdf

Previous WorkACCALandset-8Quality Assessment BandsLandset-8

RGB

Previous WorkRGBCoastal Aerosol Band

Band Number Name m Resolution

1 Coastal / Aerosol 0.4330.453 30 m

2 Visible Blue 0.4500.515 30 m

3 Visible Green 0.5250.600 30 m

4 Visible Red 0.6300.680 30 m

5 Near Infrared 0.8450.885 30 m

Previous Work

Coastal Aerosol Band

CUDAhttps://documen.tician.de/pycuda/array.html

https://documen.tician.de/pycuda/array.html

CUDA

CPU

GPU

IMPLEMENT

Get the Target Imageband_a = rasterio.open(image_file_path.format(scene_id, 1))band_g = rasterio.open(image_file_path.format(scene_id, 3))

x_min, x_max, y_min, y_max = ( 354479.71320833557, 395642.8506635118, 2764434.5394466477, 2702420.0095054144)

gt = band_a.get_transform()x_min, x_max = floor((x_min - gt[0]) / gt[1]), ceil((x_max - gt[0]) / gt[1])y_min, y_max = floor((y_min - gt[3]) / gt[5]), ceil((y_max - gt[3]) / gt[5])

band_a, band_g = ( gpuarray.to_gpu( band_a.read(1, window=((y_min, y_max), (x_min, x_max))).astype(float) ), gpuarray.to_gpu( band_g.read(1, window=((y_min, y_max), (x_min, x_max))).astype(float) )) GPU

Correction

correct = ElementwiseKernel( "double *band_a, double *band_g, double *result", "result[i] = band_a[i] + ((1 / 4.0) * (band_a[i] - band_g[i]) / band_g[i])", "correct")correct(band_a, band_g, result)

GPU

result = band1 + (1 / 4.0) * (band1 - band3) / band1

CPU

Bubble Sortcmp_swap = ElementwiseKernel( "double *x, double *y, char *xx, char *yy", ''' if(x[i] > y[i]) { double tmp_d; char tmp_u; tmp_d = x[i]; x[i] = y[i]; y[i] = tmp_d; tmp_u = xx[i]; xx[i] = yy[i]; yy[i] = tmp_u; } ''', cmp_swap")

for j in range(len(images)-1, 0, -1): for i in range(0, j): cmp_swap(images[i], images[j], images_index[i], images_index[j])

GPUCPU times: user 1.42 s, sys: 460 ms, total: 1.88 s Wall time: 1.99 s

Bubble Sort

def cmp_swap(x, y, xx, yy): shape_y, shape_x = x.shape for i in range(shape_y): for j in range(shape_x): if x[i, j] > y[i, j]: x[i, j] , y[i, j] = y[i, j], x[i, j]

for j in range(len(images)-1, 0, -1): for i in range(0, j): cmp_swap(images[i], images[j], images_index[i], images_index[j])

CPUSpend too much time. Details are as Evaluation

EVALUATION

Evaluation

mnkGPU1.99CPU5000

0

1250

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3750

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CPU GPU

ENDTHANK YOU FOR YOUR ATTENTION