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  • An elementary question on overlap

    Hello all,

    I'm new to this forum and considering the acquisition of an NN5/RD8 setup.
    Hopefully, someone can enlighten me.

    I have taken 'typical' panos by simply rotating my rig on the tripod,
    and arbitrarily adding about 10-20% overlap between my images.
    Then of course, post process/stitching.

    When I look at the rotator specs I see numbers like 18 degrees/ 20 stops,
    30 degrees/12 stops, etc.
    They all work out to an exact 360 degrees and I fail to see where the 'overlap' comes into play.

    My only guess is that when using the settings in the camera/lens database,
    the nodal point setup accounts for an overlap to be added among the image sets taken.
    Also, when setting up a 'non-standard' body/lens with Fanotec's instructions,
    the same 'overlap' will be taken into account.

    Am I on the right track, or am I just a dimwit.
    (I'd ask my wife the same question, but I already know her answer)

    Any feedback is appreciated...thanks for your patience.

    cheers,
    Enrico

    "paddle faster...I hear banjo music"

  • #2
    Re: An elementary question on overlap

    Hi enrico,

    In the database all the data is inclusive the overlap.

    Use this link, http://www.frankvanderpol.nl/fov_pan_calc.htm. I prefer 30% overlap to be more secure. Depends on the shooting site. You have to use the amount of pictures you have to take to find about the degrees you have to set on the rotator.


    Heinz

    Comment


    • #3
      Re: An elementary question on overlap

      Originally posted by enrico_953 View Post
      When I look at the rotator specs I see numbers like 18 degrees/ 20 stops,
      30 degrees/12 stops, etc.
      They all work out to an exact 360 degrees and I fail to see where the 'overlap' comes into play.
      The overlap comes from using a lens that has a wider field of view than the angle between click stops.

      Comment


      • #4
        Re: An elementary question on overlap

        Hello Enrico,

        To me, overlap is needed for your stitching software to correlate common patterns between two pictures.

        You already found out that your rotator has "stops" and "degrees" and sure enough, stops x degrees = 360?. So, in your example, 18 degrees / 20 stops means that tour rotator will allow you to stop 20 times, every 18 degrees in a 360? cycle.

        Heinz is right, 30% is a good start. The keyword though is "start". Your rotator has a finite amount of stops so in the end, it's the number of stops you key into your rotator that will set your amount of overlap.

        Let me show you how:
        Here's a link to an excellent book that has a pano calculator http://www.hdrlabs.com/tools/panocalc.html And yes, Heinz gave you the link to the creator of that pano calculator!
        Section 1: set your sensor data and the lens focal (the wider the lens, the less stops on your rotator)
        Section 2: function of your focal length and sensor dimensions, you get the Horizontal and Vertical Field of Vision (FOV). Note: the Vertival FOV of a portrait picture equals the Horizontal FOV on a landscape picture.
        Section 3: Now that you know the FOV, enter the desired overlap and the calculator gives a theoretical number of images.

        Now, this number of images is rarely an integer. You have to round it up....to match the number of stops on your rotator.

        The whole purpose of Section 4 is to recalculate the overlap given the fact that your rounded up the amount of images...

        I went through this exercise not too long ago for my D700 + RD16 rotator. Here's the result:I've added the theoretical number of images, and the rounding up to accommodate that the RD16 can do...

        I hope I did not go too deep... in summary:
        - overlap is necessary for panoramic softwares to stitch images properly
        - the actual overlap is driven by a combination of your lens orientation (portrait/landscape), focal and rotator setup
        - too little overlap will cause an improper stitching, too much overlap isn't good either (especially for your point of no parallax isn't set properly/close objects). Keeping overlaps values in mind is a must (in fact, I laminated the table in the PDF attached - and carry this table with my pano head!)

        Cheers!

        Philippe

        Comment


        • #5
          Re: An elementary question on overlap

          Interesting link you suggested.
          On my side, I have worked on excel format to calculate it regarding the position on the sphere, the angular step on the panoramic head and of course the minimum overlap you want.
          The only issue is that it is in french for the time being : Panorama calculator
          My blog : Aslan Resimler

          Comment


          • #6
            Re: An elementary question on overlap

            Hi Yves,

            I found your spreadsheet equally interesting. Do you need help translating it? Let me know!

            Bonjour Yves,
            J'ai trouve votre feuille de calcul forte interessante. Avez vous besoin d'aide pour la traduction? Dites mpi quoi.

            Thanks/Merci!

            Philippe

            Comment


            • #7
              Re: An elementary question on overlap

              Thank you for your support.
              In fact, I just need time to translate it it and I had some people asking for that new file.
              That is why I decided to put it online without the english and turkish translation.
              I guess that by the end of this week I will add the english translation.
              Thank you again.
              My blog : Aslan Resimler

              Comment


              • #8
                Re: An elementary question on overlap

                OK, translation in english is done :
                Panorama calculator
                My blog : Aslan Resimler

                Comment


                • #9
                  Re: An elementary question on overlap

                  Originally posted by YvesG View Post
                  OK, translation in english is done :
                  Panorama calculator
                  Hi YvesG,

                  Thx for the calculator and video.
                  I don't understand the 2 results in your "results details" table. what is +/-15 deg and +/- 60 deg? what is 60 deg and 130 deg?


                  Nick
                  Fanotec
                  We listen. We try harder.

                  Comment


                  • #10
                    Re: An elementary question on overlap

                    That means you need to shoot a first line at +15? and a second line at +60?.
                    And then you have to do the same at -15? and -60?.
                    Those angles are the one you can read on the arm that is supporting the camera (I am calling it the upper arm).
                    I don't know if I am clear enough.
                    My blog : Aslan Resimler

                    Comment


                    • #11
                      Re: An elementary question on overlap

                      Originally posted by YvesG View Post
                      That means you need to shoot a first line at +15? and a second line at +60?.
                      And then you have to do the same at -15? and -60?.
                      Those angles are the one you can read on the arm that is supporting the camera (I am calling it the upper arm).
                      I don't know if I am clear enough.
                      thx. that makes sense. what does 130 deg refer to?


                      Nick
                      Fanotec
                      We listen. We try harder.

                      Comment


                      • #12
                        Re: An elementary question on overlap

                        The second angle is linked to the horizontal rotation.
                        That mean you will have to take a picture every 130?.
                        Last information under this angle, is the number of pictures to be taken.
                        My blog : Aslan Resimler

                        Comment


                        • #13
                          Re: An elementary question on overlap

                          Originally posted by YvesG View Post
                          The second angle is linked to the horizontal rotation.
                          That mean you will have to take a picture every 130?.
                          Last information under this angle, is the number of pictures to be taken.
                          I am lost. Take a picture every 130 deg for 17mm eq?
                          Besides why are the results different in French and English spreadsheets?


                          nick
                          Fanotec
                          We listen. We try harder.

                          Comment


                          • #14
                            Re: An elementary question on overlap

                            There has been a bug when I translated the file.
                            To have same results, you have to select again the camera position.
                            Put the camera in vertical position and you will see that the final result is updated then.
                            Sorry for that, I am immediately updating the file to be downloaded.
                            Thank you.
                            My blog : Aslan Resimler

                            Comment


                            • #15
                              Re: An elementary question on overlap

                              Originally posted by YvesG View Post
                              There has been a bug when I translated the file.
                              To have same results, you have to select again the camera position.
                              Put the camera in vertical position and you will see that the final result is updated then.
                              Sorry for that, I am immediately updating the file to be downloaded.
                              Thank you.

                              Hi YvesG,

                              Puzzle solved. Is there a way to make a drop down list of sensor size? 35mm equivalent only works for 3:2 format sensor. It does not work for 4:3 or 16:9 sesnor.

                              Great Job!

                              Nick

                              Fanotec
                              We listen. We try harder.

                              Comment

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