PdStrip on windows XP

Discussion in 'Software' started by PdStripGui, Jul 6, 2011.

  1. Tim B
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    Tim B Senior Member

    Bill, the openDynamics project exists to improve pdStrip, and become a repository of knowledge for the software. So far I haven't had much time to really drive the development.

    The input geometry is the section shape upto the design waterline. OpenDynamics supplies a piece of code called pdGeoConv to handle the conversion from GHS to pdStrip.

    Tim B.
     
  2. PdStripGui
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    PdStripGui Junior Member

    I have read others threads in this forum concerning the output files and more particularly the sectionresults file.
    Have some of you found a user's guide to analyse the results in pdStrip?
     
  3. daiquiri
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    daiquiri Engineering and Design

  4. Martijn_vE
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    Martijn_vE Marine software developer

    I think porting the code to a "more generally accepted" programming language would be the quickest solution since it's a matter of simply translating one language to another. You don't necessarily need to have strip theory knowledge to do this. A natural side effect of porting the code is that you can use the original PDStrip executable as a benchmark/validation tool. Since both codes are the same, both programs should produce exactly the same results for a given input file.

    Once the benchmark has been completed you could extend the existing code and add more features.
     
  5. daiquiri
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    daiquiri Engineering and Design

    But as I understand (or mis-understand?), there is a problem here with understanding and interpreting PDStrip's input and/or output data, due to lack of documentation. So the safest way imho is to create a brand-new and well-documented code, so the future generations of programmers and users don't have to pass through this trouble anymore.
    Nobody should trust the results of a software which essentially appears to be a black box for everyone, imho.
     
  6. Martijn_vE
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    Martijn_vE Marine software developer

    I agree. I just indicated what is in my opinion the fastest route, not the safest.
    Besides, once translated most modern compilers will allow you to follow the program execution line by line.
    Generally this provides a great deal of insight how a program works.
    Just my 2cts.
     
  7. PdStripGui
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    PdStripGui Junior Member

    It could be a good idea to devellop a post-processor of PdStrip!
    Could openDynamics be a post-processor of PdStrip?
     
  8. CaptBill
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    CaptBill CaptBill

    Maybe this should be put out in the game development community/forums as a challenge. This is probably the ultimate challenge for 3d developers. Not only are you doing realistic waves but also computing how an object floats on top of that. May find some common interest in the subject. This is more complex than Flight sim math. Very tall order indeed. Definitely out of my league.

    The math looks to be documented well enough in the help file/readme to have the basic computations needed. I have never attempted converting formulas right of the chalkboard into code formulas though. Just doing that conversion bit might allow things to all 'click'.

    Definitely worth the effort, whatever it takes IMO.
     
  9. Tim B
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    Tim B Senior Member

    openDynamics is intended to produce post-processed output from pdStrip, as well as re-writing it and generally improving the interface. There is some information on getting RAOs from the output on the Wiki, but that's as far as I've got so far. I just haven't had the time I'd like.

    Bill, there's a significant difference between the requirements for game vessel motions (even in maneuvering simulators) and detailed "scientific" calculations. It is rare that anyone gets the funding to put them both (game front end & science back end) together, but it does happen occasionally.

    Daiquiri, you can just start from scratch, that's true, but you must prove that the results from the new code are reasonable. Typically this requires reasonably extensive testing against experimental data and other codes, including regression testing against the original. For that you need to understand the output from the original code.

    Cheers all,

    Tim B.
     
    1 person likes this.
  10. CaptBill
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    CaptBill CaptBill

    Put out a challenge with a $500 bounty and you may be surprised. Plenty of students would jump all over it i bet. Just require that the very same math is diligently adhered to. Don't think complexity of the math is a real concern just faithfully keeping the formulas right.

    Would it be suitable for the game crowd? Probably too slow for a fast action game, I would tend to imagine, unless you had a resolution setting/variable maybe. Let them work out that part.

    That way you could focus on just the testing/output analysis.

    Just an idea.
     
  11. yipster
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    yipster designer

    years back i posted here and in this forum such an idea for a online virtual test tank without reply
    think the idea is good but reason stands it wont be free, later had a look at maxsurf seakeeping and hydrostatics extension in http://www.delftship.net/
    thanks for the file Martijn and should give PdStripGui.exe a try when inspired, asked, or when i dare
     
  12. Tim B
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    Tim B Senior Member

    You also tend to find that you want to use game methods to model reasonably extreme conditions. Strip theory just doesn't work in those conditions (being a linear, small-angle, frequency domain theory), so you need to look at a full time-domain solution. Arguably this is simpler, but it still requires the same amount of rigour in testing to ensure that the results are accurate.

    Cheers,

    Tim B.
     
  13. yipster
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    yipster designer

    hi Tim and all, ah, PdStripGui.exe looks a lot better, anybody with an *.inp file to see what comes out?
     
  14. Olav
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    Olav naval architect

    yipster,

    there is an input file in the examples folder of PDStrip; see also attached file (I had to zip it to make it a format that's accepted as an attachment by the forum's software).

    The output in another window of the GUI is lots of numbers without further explanation - I'm still struggling to find out their exact meaning... :eek:
     

    Attached Files:


  15. CaptBill
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    CaptBill CaptBill

    oops, double post.
     
    Last edited: Jul 8, 2011
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