1 / 14

Thinning Procedure for Shiptracks

Thinning Procedure for Shiptracks. David Rosenfield Research Associate NOAA National Coastal Data Development Center 1021 Balch Boulevard, Suite 1003 Stennis Space Center, MS 39529 9/11/2012.

dezso
Download Presentation

Thinning Procedure for Shiptracks

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Thinning Procedure for Shiptracks David Rosenfield Research Associate NOAA National Coastal Data Development Center 1021 Balch Boulevard, Suite 1003 Stennis Space Center, MS 39529 9/11/2012

  2. Disclaimer: We are in the process of standardizing the shiptrack thinning and several other methods. This work is a proposed method arrived at from a combination of several sources and may not reflect the final method we intend on using.

  3. U:\Okeanos Explorer 2008-2009-2010-2011\2010\EX1004_Indonesia\NODC\data\0-data\vessel\EX1004_Leg3\Ship_Navigation\CNAV\: CNAV-GGA_20100722-004127.Raw CNAV-GGA_20100722-073052.Raw CNAV-GGA_20100722-101604.Raw CNAV-GGA_20100723-000000.Raw CNAV-GGA_20100724-000000.Raw CNAV-GGA_20100725-000000.Raw CNAV-GGA_20100726-000000.Raw CNAV-GGA_20100727-000000.Raw CNAV-GGA_20100728-000000.Raw CNAV-GGA_20100729-000000.Raw CNAV-GGA_20100730-000000.Raw CNAV-GGA_20100731-000000.Raw CNAV-GGA_20100801-000000.Raw CNAV-GGA_20100802-000000.Raw CNAV-GGA_20100803-000000.Raw CNAV-GGA_20100804-000000.Raw CNAV-GGA_20100805-000000.Raw CNAV-GGA_20100806-000000.Raw CNAV-GGA_20100806-150855.Raw CNAV-GGA NMEA SCS Date(MM/DD/YYYY),SCS Time(hh:mm:ss.sss),Sentence Label(None),CNAV-TIME(hhmmss),CNAV-LAT(deg),CNAV-LAT Units,CNAV-LON(deg), 07/26/2010,00:00:01.471,$GPGGA,000001.00,0216.124127,N,12449.075605,E,2,09,1.1,22.604,M,65.744,M,10.0,0025*44 07/26/2010,00:00:02.471,$GPGGA,000002.00,0216.124154,N,12449.075612,E,2,09,1.1,22.566,M,65.744,M,10.0,0025*42 07/26/2010,00:00:03.471,$GPGGA,000003.00,0216.124176,N,12449.075607,E,2,09,1.1,22.682,M,65.744,M,9.0,0025*76 07/26/2010,00:00:04.472,$GPGGA,000004.00,0216.124197,N,12449.075601,E,2,09,1.1,22.797,M,65.744,M,10.0,0025*45 07/26/2010,00:00:05.472,$GPGGA,000005.00,0216.124185,N,12449.075604,E,2,09,1.1,22.801,M,65.744,M,10.0,0025*42 07/26/2010,00:00:06.472,$GPGGA,000006.00,0216.124119,N,12449.075601,E,2,09,1.1,22.772,M,65.744,M,10.0,0025*4A 07/26/2010,00:00:07.472,$GPGGA,000007.00,0216.124052,N,12449.075599,E,2,09,1.1,22.741,M,65.745,M,10.0,0025*46 07/26/2010,00:00:08.472,$GPGGA,000008.00,0216.124001,N,12449.075584,E,2,09,1.1,22.700,M,65.744,M,10.0,0025*47 07/26/2010,00:00:09.472,$GPGGA,000009.00,0216.124011,N,12449.075558,E,2,09,1.1,22.693,M,65.744,M,9.0,0025*75 07/26/2010,00:00:10.472,$GPGGA,000010.00,0216.124038,N,12449.075558,E,2,09,1.1,22.742,M,65.744,M,10.0,0025*43 07/26/2010,00:00:11.472,$GPGGA,000011.00,0216.124050,N,12449.075586,E,2,09,1.1,22.717,M,65.744,M,10.0,0025*4F 07/26/2010,00:00:12.456,$GPGGA,000012.00,0216.124051,N,12449.075614,E,2,09,1.1,22.669,M,65.744,M,10.0,0025*4D 07/26/2010,00:00:13.472,$GPGGA,000013.00,0216.124051,N,12449.075625,E,2,09,1.1,22.666,M,65.744,M,10.0,0025*41 SCS Date(MM/DD/YYYY), SCS Time(hh:mm:ss.sss), Sentence Label(None), CNAV-TIME(hhmmss), CNAV-LAT(deg), CNAV-LAT Units, CNAV-LON(deg), CNAV-LON Units, CNAV-Fix Quality(*NONE*), CNAV-Sat(*NONE*), CNAV-HDOP(*NONE*), CNAV-Alt(Meters), CNAV-Alt-M(*NONE*), CNAV-Geoid(*NONE*), CNAV-Geoid-M(*NONE*), CNAV-?(*NONE*), CNAV-GGA-Chksum(*NONE*)

  4. thinshiptrack.m • octave> [ipos,opos]=thinshiptrack(eps,dist,nsec); • Three step process • Save record every ‘nsec’ seconds • Save ‘ipos’ as ascii file • Save ipos as a workspace variable • Perform Douglas Peucker optimization • octave> list=douglaspeucker(x,y,points,eps,dist); • octave> opos=ipos(:,list); • Save ‘opos’ as ascii file • Return opos as a workspace variable • Convert to (and save) a .kml file

  5. STEP 1 of thinshiptrack.m • Save record every ‘nsec’ seconds For each file: if nsec=6 for example… CNAV-GGA_20100722-004127.Raw CNAV-GGA_20100722-073052.Raw DateString,Tag,Date#,Lon,N,Lat,E,,,,,,Elev,,,, CNAV-GGA_20100722-101604.Raw ---------------------------------------------- CNAV-GGA_20100723-000000.Raw CNAV-GGA_20100724-000000.Raw CNAV-GGA_20100725-000000.Raw CNAV-GGA_20100726-000000.Raw CNAV-GGA_20100727-000000.Raw CNAV-GGA_20100728-000000.Raw CNAV-GGA_20100729-000000.Raw CNAV-GGA_20100730-000000.Raw CNAV-GGA_20100731-000000.Raw CNAV-GGA_20100801-000000.Raw CNAV-GGA_20100802-000000.Raw CNAV-GGA_20100803-000000.Raw saves variable creates ascii file CNAV-GGA_20100804-000000.Raw CNAV-GGA_20100805-000000.Raw DateString Date# Lon Lat Elev CNAV-GGA_20100806-000000.Raw ---------------------------------- CNAV-GGA_20100806-150855.Raw ipos is a [4x100K] matrix in Octave/MATLAB workspace ipos=[Date#;lon;lat;elev] 07/26/2010,00:00:01.471,$GPGGA,000001.00,0216.124127,N,12449.075605,E,2,09,1.1,22.604,M,65.744,M,10.0,0025*44 07/26/2010,00:00:02.471,$GPGGA,000002.00,0216.124154,N,12449.075612,E,2,09,1.1,22.566,M,65.744,M,10.0,0025*42 07/26/2010,00:00:03.471,$GPGGA,000003.00,0216.124176,N,12449.075607,E,2,09,1.1,22.682,M,65.744,M,9.0,0025*76 07/26/2010,00:00:04.472,$GPGGA,000004.00,0216.124197,N,12449.075601,E,2,09,1.1,22.797,M,65.744,M,10.0,0025*45 07/26/2010,00:00:05.472,$GPGGA,000005.00,0216.124185,N,12449.075604,E,2,09,1.1,22.801,M,65.744,M,10.0,0025*42 07/26/2010,00:00:06.472,$GPGGA,000006.00,0216.124119,N,12449.075601,E,2,09,1.1,22.772,M,65.744,M,10.0,0025*4A 07/26/2010,00:00:07.472,$GPGGA,000007.00,0216.124052,N,12449.075599,E,2,09,1.1,22.741,M,65.745,M,10.0,0025*46 07/26/2010,00:00:08.472,$GPGGA,000008.00,0216.124001,N,12449.075584,E,2,09,1.1,22.700,M,65.744,M,10.0,0025*47 07/26/2010,00:00:09.472,$GPGGA,000009.00,0216.124011,N,12449.075558,E,2,09,1.1,22.693,M,65.744,M,9.0,0025*75 07/26/2010,00:00:10.472,$GPGGA,000010.00,0216.124038,N,12449.075558,E,2,09,1.1,22.742,M,65.744,M,10.0,0025*43 07/26/2010,00:00:11.472,$GPGGA,000011.00,0216.124050,N,12449.075586,E,2,09,1.1,22.717,M,65.744,M,10.0,0025*4F 07/26/2010,00:00:12.456,$GPGGA,000012.00,0216.124051,N,12449.075614,E,2,09,1.1,22.669,M,65.744,M,10.0,0025*4D 07/26/2010,00:00:13.472,$GPGGA,000013.00,0216.124051,N,12449.075625,E,2,09,1.1,22.666,M,65.744,M,10.0,0025*41 07/26/2010,00:00:14.472,$GPGGA,000014.00,0216.124072,N,12449.075628,E,2,09,1.1,22.669,M,65.744,M,10.0,0025*45 07/26/2010,00:00:15.456,$GPGGA,000015.00,0216.124079,N,12449.075626,E,2,09,1.1,22.751,M,65.745,M,9.0,0025*72 07/26/2010,00:00:16.472,$GPGGA,000016.00,0216.124060,N,12449.075623,E,2,09,1.1,22.826,M,65.744,M,9.0,0025*72 07/26/2010,00:00:17.472,$GPGGA,000017.00,0216.124028,N,12449.075627,E,2,09,1.1,22.814,M,65.744,M,10.0,0025*42 07/26/2010,00:00:18.472,$GPGGA,000018.00,0216.124035,N,12449.075640,E,2,09,1.1,22.725,M,65.744,M,10.0,0025*4D 07/26/2010,00:00:19.472,$GPGGA,000019.00,0216.124065,N,12449.075641,E,2,09,1.1,22.693,M,65.744,M,10.0,0025*44 07/26/2010,00:00:06.472 3.971281 124.817927 2.268735 22.772 07/26/2010,00:00:12.456 3.971350 124.817927 2.268734 22.669 07/26/2010,00:00:18.472 3.971420 124.817927 2.268734 22.725

  6. STEP 2 of thinshiptrack.m • Perform Douglas Peucker optimization Simple lines of several points are reduced to a 2 point line. n=6n=2 More complex paths are broken down to smaller lines... n=13 ...and each are reduced to a 2 point line. n=4 This method is called “recursion.”

  7. STEP 2 of thinshiptrack.m • Standard Douglas Peucker optimization • Epsilon: some small % of total distance max perpendicular dist epsilon * total dist total distance n=15

  8. STEP 2 of thinshiptrack.m • Addition to Douglas Peucker optimization • BaseDistance: some small (1-1000m) distance When total distance is smaller than BaseDistance, all points within the line are removed. And we’re done! n=7

  9. thinshiptrack.m • Overview

  10. thinshiptrack.m • Evaluation In your “C:\Octave\student\” directory there is a file you will run in Octave called thinshiptrack.m (runs douglaspeucker.m) The basic call is: opos=thinshiptrack(eps,dist,nsec) so you can either define eps, dist and nsec, or plug in values octave>cd ../../student octave>eps=0.01;dist=1;nsec=6; octave>opos1=thinshiptrack(eps,dist,nsec); octave>opos2=thinshiptrack(0.01,100,60); octave>whos Details on opos1 and opos2 come up on your screen. Exploring your student directory, you should see two new *.kml file that you just created. Drag both of these into Google Earth and change one shiptrack’s color to red. Repeat to fill out the following table.

  11. thinshiptrack.m • Evaluation • Otherwise use eps=1%, nsec=60, and dist=10m

  12. thinshiptrack.m • Error Calculation • But how much do they differ quantitatively? • First run the highest resolution possible • octave>eps=0.0001;dist=1;nsec=1; • octave>opos0=thinshiptrack(eps,dist,nsec); • That took a little while…200s on my box • octave>eps=0.1;dist=1000;nsec=600; • octave>opos3=thinshiptrack(eps,dist,nsec); • This one’s much faster…0.5s • octave>whosopos* • Details on opos0-3 come up on your screen. • Now let’s perform an error test on these shiptracks • octave>errortest(opos3) • octave>errortest(opos2) • octave>errortest(opos1) • OR • octave>errortest(thinshiptrack(eps,dist,nsec))

  13. thinshiptrackBJ4.m • Applying the thinshiptrack.m routine to a shiptrack from the Baruna Jaya IV was done for you, but you may want to repeat the process for yourself. • Given High-Resolution Multibeam Data (~300MB x y z ascii file) filter data using a 200 point triangular window running average over multiple (100) iterations • Subsample by a 100 (from an original 9 million points) gives one a good representation of the shiptrack • Repeat Douglas Peuker thinning by modifying thinshiptrack.m

  14. Thanks!Any Questions?

More Related