Good day, everyone. I would like to ask a question on 3d displaying. I have this data file. dat1.txt: Sokcho 38.2500 128.5667 17.8 Cheorwon 38.1500 127.3000 154.2 Dongducheon 37.9000 127.0667 112.5 Daeguallyeong 37.6833 128.7667 842.5 Chuncheon 37.9000 127.7333 76.8 I read this file as follows. readcol, 'dat1.txt', city, lat, lon, alt, format = 'A, 3F' And then I am going to display these data into 3d. x = lon, y = lat, z = alt Based on the a procedure on www.dfanning.com, I tried this way but the results was not what I wanted to. Is there anyone to help me? ----------------------------------------------------------------------------------- PRO SCATTER3D_altitude ; Read the data file. readcol, 'dat1.txt', city, lat, lon, alt, format='A, 3F7.2' n=n_elements(lat) vsym, 24 , /fill ; Load a color table and create colors for the scatterplot. LOADCT, 38, NCOLORS=!D.N_COLORS-1 TVLCT, 70, 70, 70, !D.N_COLORS-1 zcolors = BYTSCL(alt, TOP=!D.N_COLORS-2) ; Set the 3D coordinate space with axes. SURFACE, DIST(5), /NODATA, /SAVE, XRANGE=[125,132], $ YRANGE=[33,39], ZRANGE=[0, 900], CHARSIZE=1.5, COLOR=!D.N_COLORS-2, BACKGROUND=!D.N_COLORS-1, $ ; Plot the random points in 3D space with a diamond shape. PLOTS, lon, lat, alt, PSYM=4, COLOR=zcolors, /T3D ; Connect the data points to the XY plane of the plot. FOR j=0, n-1 DO PLOTS, [lon(j), lon(j)], [lat(j), lat(j)], [0, alt(j)], COLOR=zcolors(j), /T3D END