(4) Flying over topography — GMT 5.1.1 documentation

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# (4) Flying over topography

Our next animation simulates what an imaginary satellite might see as it passes in a great circle from New York to Miami at an altitude of 160 km. We use the general perspective view projection with grdimage and use project to create a great circle path between the two cities, sampled every 5 km. The main part of the script will make the DVD-quality frames from different view points, draw the path on the ground, and add frame numbers to each frame. As this animation generates 355 frames we can use 3rd party tools to turn the image sequence into a MPEG-4 movie. Note: At the moment, grdview cannot use general perspective view projection to allow “fly-through” animations like Fledermaus; we expect to add this functionality in a future version.

    #!/bin/bash
    #               GMT ANIMATION 04
    #
    # Purpose:      Make DVD-res Quicktime movie of NY to Miami flight
    # GMT progs:    gmt gmtset, gmt gmtmath, gmt psbasemap, gmt pstext, gmt psxy, gmt ps2raster
    # Unix progs:   awk, mkdir, rm, mv, echo, qt_export, cat
    # Note:         Run with any argument to build movie; otherwise 1st frame is plotted only.
    #
    # 1. Initialization
    # 1a) Assign movie parameters
    REGION=-Rg
    altitude=160.0
    tilt=55
    azimuth=210
    twist=0
    Width=36.0
    Height=34.0
    px=7.2
    py=4.8
    dpi=100
    name=anim_04
    ps=.ps

    # Set up flight path
    gmt project -C-73.8333/40.75 -E-80.133/25.75 -G5 -Q > $$.path.d
    frame=0
    mkdir -p frames
    gmt grdgradient USEast_Coast.nc -A90 -Nt1 -G$.nc
    gmt makecpt -Cglobe -Z > $$.cpt
    while read lon lat dist; do
    	file=`gmt_set_framename  `
    	ID=`echo  | $AWK '{printf "%04d\n", $1}'`
    	gmt grdimage -JG////////7i+ \
    		 -P -Y0.1i -X0.1i USEast_Coast.nc -I$.nc -C$$.cpt \
    		--PS_MEDIA=ixi -K > $$.ps
    	gmt psxy -R -J -O -K -W1p $$.path.d >> $$.ps
    	gmt pstext -R0//0/ -Jx1i -F+f14p,Helvetica-Bold+jTL -O >> $$.ps <<< "0 4.6 "
    	if [ $# -eq 0 ]; then
    		mv $$.ps
    		gmt_cleanup .gmt
    		gmt_abort ": First frame plotted to .ps"
    	fi
    	gmt ps2raster $$.ps -Tt -E
    	mv $$.tif frames/.tif
            echo "Frame  completed"
    	frame=`gmt_set_framenext `
    done < $$.path.d
    if [ $# -eq 0 ]; then
    	echo "anim_04.sh: Made  frames at 480x720 pixels placed in subdirectory frames"
    #	qt_export $$/anim_0_123456.tiff --video=h263,24,100, _movie.m4v
    fi
    # 4. Clean up temporary files
    gmt_cleanup .gmt

Flying over topography.

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