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Question: photoreal groundpolygon where to start

Discussion in 'Airport Design General' started by RobdeVries, 28/2/07.

  1. RobdeVries

    RobdeVries

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    Hello,


    I'd like to ask you for a little bit of help on designing photoscenery or more precise a photoreal ground polygon for an little airport.


    I've been pondering on making Tieton State in Washington State as an addon for MegaScenery's Pacific North West photoscenery and the default FS9 scenery.

    Recently I noticed that Google (not to be published) or USAPhotomaps has some fairly high res pics of Tieton State and I'd like to put them into sim as bgl. More or less like Richard Goldstein did with his Georender series or Bob B with his great airport addons.

    My big question is of course what steps does one have to take from picture to photoscenery/photoreal ground polygon. What tools are needed, do and don't etc..

    I'm all new to this and am patient and eager to learn only I'm not very technical..:rolleyes: I did a search here but a lot of questions and answers are of course contextual and do not depict the whole picture.

    Many thanks in advance.
    Rob de Vries
    The Netherlands
  2. RobdeVries

    RobdeVries

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    no one?

    Mmm. I though it was the right forum to post such a question. 35 views but no response. Does nobody have a clue?

    Thanks in advance,
    Rob
  3. bob5568

    bob5568

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    Rob, please be patient.

    Are you designing for fs9 or fsx?

    Tieton State would be a nice project for you!

    Bob
  4. bob5568

    bob5568

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    Sorry, I see on rereading you specify fs9.

    Tieton State would be a nice project for you! To make a photoreal ground poly in fs9, my best results come from designing in gmax.

    first you want great source photo, and you want that photo to be projected in wgs84 datum, geographic projection. Converting the photo is simple if you have a GIS tool, or a hassle if you don't. I can help here if you need it.

    Once you have a good source photo, you need to be able to relate the geographic coverage of the photo to pixels, and also to meters.

    Again, easy to do with either a good gis tool, or with very acurate information about landmarks contained in the photo. One source of information is the airport/facilities directory, which shows runways in length units, meters or feet, and you'll find using the runway ends to be a pretty good set of landmarks.

    I usually make an excell spreadsheet in which i list the 3 units of distance between a horizontal set of landmarks and a vertical set of landmarks. 1. distance in degrees 2. distance in meters 3. distance in pixels

    With that, you can now calculate 4 ratios that are useful, 1. degrees/pixel (horizontal), 2. degrees/pixel (vertical), 3. meters/pixel (horizontal), and meters/pixel (vertical).

    That's the hard work.

    Now, you look at your photo and let your artist side take control for a minute, decide where the outside edge of your project is based on the photo.

    Crop the photo to that extent.

    Now a little planning is needed. You'll need to eventually make textures of parts of this image, so the overall image extent is easiest if it consists of an even multiple of the texture sizes, 256x256 pixels, or 512x512 pixels or 1024x1024 pixels, or rectuangular combinations. So I make a choice of texture size, I usually use 512x512. Then I'll make a multiples chart in excell, by listing the product of 512 x 1,2,3,4,.... Then I know the extent I've chosen for my image, and I'll choose the closest multiple as the ideal extend of my image. Now, if you want, you can go back and crop the image bigger or slightly smaller to match, or you can just add dead image pixels to the image, we'll deal with making it look nice later. If you choose to just fake the image into the right size, just add canvas, do not "resize" the image, which resamples it. Leave the new "border" blank. Whatever the default shows it is fine. That part wont make it to the final result. The end result is a photo with a width and height that's a multiple of the texture size.

    Your photo width in pixels, times your horizontal m/pixels tells you the width of the gmax polygon, similarly your photo height in pixels times your vertical m/pixels tells your the height in meters of your gmax polygon. Now go to gmax and make a plane using the meters from this exercise. set your width and height subsections to the multiples of your texture, so that you have individual polygons for each square of the texture you plan to drap on the polygon.

    Make your textures from the main image now. You cut up the texture per your plan.

    Now you multitexture the plane. I do a wierd way of this, others are more elegant. I go into poly mode and "detach" each of the poly sections, texture each one with the material appropriate for that segment. Then when all done, I "attach" the polys together. This automatically makes the material a multi-material.

    Now you have a square plane with an awesome high res image of your airport and surroundings but with an ugly border.

    What I do now is build a cutting tool in gmax. The tool takes the shape of the real extend I desire to see displayed in fs9, and then extends beyond the edge of the plane. I do this tool in quadrants as gmax can be fussy about complex shapes doing boolean cuts. So, I make a 2d line over the edge of the place I want to end the polygon, and when I get about a quarter of the way around, I just turn the line to go beyond the edge, and then continue around until the shape covers 1/4 of the area of the plan that I'd like to dispose of.

    Now, I extrude the shape. Now I go into "border" mode, and highlight the open edge of the extrusion and click "cap". Now the tool is a solid. Position the tool in z, so that it intersects the plane. Now select the plane, and tell gmax you are making a boolean object. Select the tool as part "b" and select "cookie cutter", and then subtract b from A. Voila...your plane has 1/4 of it shaped irregularly, and still decorated with high res imagry. Now repeat for the other 4 quarters, and you have a beautiful ground polygon ready for export.

    Export needs to be done with the fs2002 makemdl, with a makemdl.cfg line inserted that instructs Keepfiles=1. (I may have that inaccurate, this is typed from memory, I'm not at my dev computer) You need to establish a ref point for the plane prior to export, which will have a lat/long that agrees with fs world. This can be the end of a runway. The natural ref point won't be there but you can more the ref point using the motion button on gmax, and the affect pivot only setting. Provide that coordinate pair to the export screen in makemdl.

    Once you export, you will have an asm version of the export file, and an asm_0 version as well.

    Find the code call "addobj......", and change that to addcat.....and you can add a comma and a level here. Then delete the shadowcall statement. Arno has a seperate post on this site that details this tweak.

    Then recompile using bglc.exe

    Now you add your bgl file, and enjoy the result.
    Bob


    PS...forgot to mention that you still need to make fs textures of the gmax material squares. convert them to dxt1 using imagetool.
    Last edited: 2/3/07
  5. michaelblackbird

    michaelblackbird

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    Hello

    Very interesting topic and explanation.

    Bob, you spoke about a GIS tool to transform the picture in WGS84.
    I want to convert a Lambert II (from IGN - France) projection in WGS84. What tool will you choose ?

    Bye
    Michel
  6. arno

    arno Administrator Staff Member FSDevConf team Resource contributor

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    Hi Michel,

    It is not really an easy tool to use, but I would use FwTools. It is basically command line driven, but it is very powerful. The only problem for some users might be the lack of a GUI.

    I have used it to convert images from the Dutch Rijksdriehoeks coordinate system to WGS84 as well.
  7. bob5568

    bob5568

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    Hi Michael, I'm spoiled now, as I finally decided to spend some money on tools. I bought Global Mapper, it costs about $250 US, but among its features, it does projection conversions beautifully.

    Assuming Arno's suggestion is freeware you may want to try that out first. If you image is smallish, I could reproject it for you.

    Bob
  8. michaelblackbird

    michaelblackbird

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    Hello

    Unfortunetly, my images are too heavy I think, thanks for trying to help me.
    But I know someone (working in a GIS company but without experience in developping for FS) that have this software Global Mapper. I've seen it and it seems easy, but I don't know how to start.

    I want also to use other aerial pictures to do a photomesh scenery bigger than an airport. And I don't know again how to use it with Terrabuilder.

    Could you give us a little explanation to start wit hthe good features. I thought about the Capture Screen contents to image (BMP)....???

    Anyway many thanks
    Bye
  9. bob5568

    bob5568

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    simple to operate global mapper, just open your file and click on "tools", then "configure"

    Then click on the tab marked "projection", you'll see the projection is a choice and datum, choose geographic and wgs84, and your done, hit ok..and you've got your image converted.

    I do use the capture screen content to image control commonly, it allows you to generate a world file that you'd need if you wish to compile using the geotiff format.

    Best,
    Bob
  10. michaelblackbird

    michaelblackbird

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    Hello

    Thanks
    Have you find how to know coordinates of one of the four corners ?
  11. bob5568

    bob5568

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    Michael, you have to know that to start with...either with a reference from a map or a world metadata file you might have delivered from the source file location.

    Best,
    Bob
  12. michaelblackbird

    michaelblackbird

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    Hello

    OK now I have a bitmap corrected but not with global mapper. I've applied a rotation with PSP. I didn't find how to transform lambert II to WGS84 projection.

    I've made in gmax the multisquare poly, detach each square. But I have difficulties to apply material in the correct way. I've "won" for 2 objects (2 square polys) but by undirect ways and I can't redo it :confused: .

    Can you explain in detail the right method to wrap each texture please on each plane object.

    Bye
  13. michaelblackbird

    michaelblackbird

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    I've found

    Just after apply a new material to the object I've click on the UVW Map modifier and the texture is applied correctly.

    It's a long way to do all the objects..... :)
  14. MoToCroSs986

    MoToCroSs986

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    I have used global mapper like you have said, which corner do you need to know the log/lat for? Do you use degrees minutes or decimal degrees. What is the file type that you start with?

    Thanks
  15. bob5568

    bob5568

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    Not clear on what you need...if you import usgs photos into global mapper, they are already georeferenced.

    If you have a picture you wish to georeference, you can align the pic to any knowns...could be an airport runway for instance. If you import an image without reference information, the rectify (georeference) dialogue is supposed to come up automatically. Of course you need sufficient knowns of point locations to pin the image down.
  16. Skydvdan1

    Skydvdan1

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    Can Global Mapper convert from NAD83 to WGS84? Can it create Geotiffs?
  17. bob5568

    bob5568

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    yes to both questions.
  18. Skydvdan1

    Skydvdan1

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    Now the question is can I part with $279. How is the learning curve?
  19. bob5568

    bob5568

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    I had no trouble with it. Within a few hours at most, you'll be successful with anything you're likely to need. Good help is included.

    The money is an issue. I avoided spending it for over a year, but in the end I'm glad I did.

    Bob
  20. Skydvdan1

    Skydvdan1

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    What is the process of converting NAD83 to WGS84 imagery? Do I just have to re-georeference the geotiff?
    Last edited: 31/5/07

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