Dear IDL community, I wrote a little program which calculates x, y, and z ground control points (gcp) for each pixel of an image. To do this, I am placing pitch, roll, and yaw parameters into a formula given by Hongjian and Shukai (2004) The problem I have is that my program works fine for small images e.g. if I do have only 100 scanlines. However, if I try to calulate the gcps for larger images (e.g. > than 5000 scanlines) the computer crashes because it uses too much active memory. I am suspecting that too much active memory is necessary for large images due to the therefore resulting large loops and arrays in my program. Since I am new to programming I do not really know how to reduce the active memory necessary to run the program for large images. It would be great if somebody has a suggestion, how to reduce the amount of active memory necessary to run this program so that the program can also be used to calculate gcp's for large images. I really appreciate your time and help with this Best regards, Jan ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; ; Programmer: Jan Eitel ; Last update: 3-17-2006 ; Program to calculate x, y, and z ground control points (gcp's) by using pitch, roll, and yaw variables provided by ; the intertial navigation system. ;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; pro easy_shift ;# of columns in the image Columns = 752 ;# of rows in the image Rows = 100 ;# of loops rep = (Rows-1) ;; Type in average flying height (fh) fh = 4000 ;; Type in average elevation elev = 2583 ;; Convert flying height and elevation to meters fh = fh*0.3048 elev = elev*0.3048 ;; Calculate flying height above sea level fhasl = fh - elev ;; Field of view (FOV) per scanline fov = 15.2483314 * (3.14159265/180)/376 ;; Create array. Array will be used to place the calculated internal geometry values into xyz_array = make_array(3, 752, /double, value = 0) ;; calculate the internal geometry of the sensor: for i = 1, 376 do begin fovsl = fov * i x = tan(fovsl)*fhasl y = x - xyz_array[0, i + 374] z = fhasl/cos(fovsl) b = 375 + i xyz_array[0,b] = x xyz_array[1,b] = y xyz_array[2,b] = z endfor for i = 1, 376 do begin b = 376 - i c = 375 + i xyz_array[0,b] = xyz_array[0, c] * (-1) xyz_array[1,b] = xyz_array[1, c] * (-1) xyz_array[2,b] = xyz_array[2, c] endfor ;; read in roll, pitch, yaw, xgps, ygps, zgps openr, 1, 'C:/HC/input1.txt' ins = dblarr(5, Rows) readf, 1, ins close, 1 ;; i is the scanline number (starting with scanline #1) i = 0 o = ins[0, i] w = ins[1, i] k = ins[2, i] ;; populate matrix given in Hongjian and Shukai (2004) and calculate gcp (ground control points) a1 = cos(k)*cos(o) a2 = -cos(k)*sin(o)*sin(w) - sin(k)*cos(w) a3 = sin(k)*cos(o) b1 = sin(k)*cos(o) b2 = -sin(k)*sin(o)*sin(w)+cos(k)*cos(w) b3 = -sin(k)*sin(o)*cos(w)-cos(k)*sin(w) c1 = sin(o) c2 = cos(o)*sin(w) c3 = cos(o)*cos(w) matrix1 = make_array(3, 3, /double, value = 0) matrix1[0,0] = a1 matrix1[1,0] = a2 matrix1[2,0] = a3 matrix1[0,1] = b1 matrix1[1,1] = b2 matrix1[2,1] = b3 matrix1[0,2] = c1 matrix1[1,2] = c2 matrix1[2,2] = c3 xgps = ins[3, i] ygps = ins[4, i] zgps = fhasl matrix3 = make_array(1, 3, /double, value = 0) matrix3[0,0] = xgps matrix3[0,1] = ygps matrix3[0,2] = zgps matrix2 = xyz_array matrix2 = matrix2[0:2,0] matrix2 = transpose(matrix2) cf = (matrix1 ## matrix2) + matrix3 cf_x = cf[0,0] cf_y = cf[0,1] cf_z = cf[0,2] out_x = (cf_x) out_y = (cf_y) out_z = (cf_z) for g = 1, 751 do begin matrix2 = xyz_array matrix2 = matrix2[0:2,g] matrix2 = transpose(matrix2) cf = (matrix1 ## matrix2) + matrix3 cf_x = cf[0,0] cf_y = cf[0,1] cf_z = cf[0,2] out_x = [[out_x], [cf_x]] out_y = [[out_y], [cf_y]] out_z = [[out_z], [cf_z]] endfor for i = 1, rep do begin o = ins[0, i] w = ins[1, i] k = ins[2, i] ;;populate matrix given in Hongjian and Shukai (2004) and calculate gcp (ground control points) a1 = cos(k)*cos(o) a2 = -cos(k)*sin(o)*sin(w) - sin(k)*cos(w) a3 = sin(k)*cos(o) b1 = sin(k)*cos(o) b2 = -sin(k)*sin(o)*sin(w)+cos(k)*cos(w) b3 = -sin(k)*sin(o)*cos(w)-cos(k)*sin(w) c1 = sin(o) c2 = cos(o)*sin(w) c3 = cos(o)*cos(w) matrix1 = make_array(3, 3, /double, value = 0) matrix1[0,0] = a1 matrix1[1,0] = a2 matrix1[2,0] = a3 matrix1[0,1] = b1 matrix1[1,1] = b2 matrix1[2,1] = b3 matrix1[0,2] = c1 matrix1[1,2] = c2 matrix1[2,2] = c3 xgps = ins[3, i] ygps = ins[4, i] zgps = fhasl matrix3 = make_array(1, 3, /double, value = 0) matrix3[0,0] = xgps matrix3[0,1] = ygps matrix3[0,2] = zgps matrix2 = xyz_array matrix2 = matrix2[0:2,0] matrix2 = transpose(matrix2) cf = (matrix1 ## matrix2) + matrix3 cf_x = cf[0,0] cf_y = cf[0,1] cf_z = cf[0,2] out_xx = (cf_x) out_yy = (cf_y) out_zz = (cf_z) for g = 1, 751 do begin matrix2 = xyz_array matrix2 = matrix2[0:2,g] matrix2 = transpose(matrix2) cf = (matrix1 ## matrix2) + matrix3 cf_x = cf[0,0] cf_y = cf[0,1] cf_z = cf[0,2] out_xx = ([[out_xx], [cf_x]]) out_yy = ([[out_yy], [cf_y]]) out_zz = ([[out_zz], [cf_z]]) endfor out_x = ([[out_x], [out_xx]]) out_y = ([[out_y], [out_yy]]) out_z = ([[out_z], [out_zz]]) endfor ;Create arrays to place x, y, z gcp into output_x = make_array(752, rows, / string, value = 0) output_y = make_array(752, rows, /string, value = 0) output_z = make_array(752, rows, /string, value = 0) counter = lindgen(752, rows) for i = 0, rep do begin for j = 0, 751 do begin counter1 = counter[j, i] output_x [j, i] = out_x [0, counter1] output_y [j, i] = out_y [0, counter1] output_z [j, i] = out_z [0, counter1] endfor endfor ;Write x gcp to file data = output_x ColumnHeaders=columnHeaders Filename= 'C:/HC/x_gcp.txt' width = 10000 ;define delimiter Delimiter = String(9B) OpenW, lun, filename, /Get_Lun, Width=width sData = StrTrim(data,1) for i = 0, rep do begin sData[751, i] = sData[751, i] endfor PrintF, lun, sData ; Close the file. Free_Lun, lun ; Write y gcp to file data1 = output_y ColumnHeaders=columnHeaders Filename= 'C:/HC/y_gcp.txt' width = 10000 Delimiter = String(9B) OpenW, lun, filename, /Get_Lun, Width=width sData = StrTrim(data1,1) for i = 0, rep do begin sData[751, i] = sData[751, i] endfor PrintF, lun, sData Free_Lun, lun ;Write y gcp to file data2 = output_z ColumnHeaders=columnHeaders Filename= 'C:/HC/z_gcp.txt' width = 10000 Delimiter = String(9B) OpenW, lun, filename, /Get_Lun, Width=width sData = StrTrim(data2,1) for i = 0, rep do begin sData[751, i] = sData[751, i] endfor PrintF, lun, sData Free_Lun, lun END