More questions about tiles, levels etc

  • I think I've read most of the tutorials etc on geoconversion, but there are still one or two things I'd like to get clear in my head. I'd be very grateful if anybody can find time to answer any of these!


    1. The size of a level 9 tile appears to be roughly 1 deg x 1 deg. (The size in km obviously varies with latitude.) Is it exactly 1x1 deg, and do its boundaries coincide exactly with whole degrees of latitude and longitude? The reason I ask is that one way of avoiding masking problems is to snap to a level 9 tile in GeoConvertHelper. However, unless you know exactly where the level 9 tile is, you would have to gather images from FSET in an areas of roughly 2x2 deg to be sure of capturing one whole level 9 tile.


    2. Do the boundaries of the higher level tiles coincide exactly with boundaries of lower level ones? (I assume they do.) e.g. Are there 4 level 10 tiles precisely within one level 9 tile, etc etc?


    3. I assume that the higher level tiles are not visible beyond a certain height/distance, so that your computer does not have to process information that is too small for your eye/monitor/VR headset to resolve. Is that correct? Does anybody know roughly what these distances are for different levels? The reason I ask is that I shall mostly be gliding at no more than 1000 m above the ground. Could I get away with just levels 13, 14 and 15 for example? (I could determine this by experiment, but I was just wondering if anybody already knows the answer.)


    4. Do the black (masked) parts of lower level tiles obscure higher level tiles that exist in the black region? Is this why masking causes such problems? However I assume you would still see the higher level tiles if you flew low enough?


    5. I always set FSET to a resolution of -1 (0.25 m). This means that it would take 24 hours at the very least to gather images to cover a whole level 9 tile. An area of 0.2 x 0.2 deg (roughly 20 x 20 km) seems more reasonable time-wise. My thinking is that one way forward for me would be to set GeoCovertHelper to give me no masked images (by unticking the box). This would mean that I would only get maybe level 12 tiles and higher within a 20x20 km box, since tiles at all levels lower than 12 would be too big. They would fall partially outside the area and would therefore be masked - and hence rejected. If I wanted to extend my scenery area I could then geoconvert another neighbouring 20x20 km square with a 50% overlap with the first 20x20 km square. I could then dump all the files into the same folder and reject the duplicates. This way I ought to get complete and seamless coverage at level 12 and higher without any masking problems. Does that make sense?



  • Hi Ian,


    excellent questions, I see you are dealing with the subject!


    1. Level 9 divides the earth into 512 tiles. So the grid width is 360 degrees / 512 tiles = 0.703125 degrees per tile.
    While the longitude values is constant, it differs in latitude direction depending from the latitude.
    I published the code in another thread, but have to check it and will append it here again.


    2. Yes, they do exactly.


    3. I don't know when the higher levels will be visible during approach, it may even be different for different settings. For your gliding you may try with your suggested levels. If it is not sufficient, you can later run the converter again and add just the lower levels 11 and 12.


    4. No, the masks do only affect their related level. You can see the level in the name of the tiles.


    5. Yes, I like your approach. Skip level 9 and 11, run level 12 and higher. Have an overlap in your aerial images and create a single output folder without mask files in it.


    Hope you succeed and give some feedback.

    Rodeo

  • Hi Rodeo


    Many thanks for your very clear answers, as always. I'm now in the process of trying out my own idea and I will certainly let you know how I get on. It's good to know that I can always add the lower levels later if it's not satisfactory.


    Cheers Ian

  • Quick supplementary question to add to my list .....


    There are 4 level 1 tiles covering the whole earth. Do they all meet in the middle at lat 0, long 0? If that is the case it has just occurred to me that it would be relatively simple to calculate the position of any level of tile at any point on the earth's surface.


    (Just to be clear, I am assuming that each level 1 tile has dimensions of 90 deg in latitude and 180 deg in longitude. So a level 2 tile is 45 deg in latitude and 90 deg in longitude, and so on. Hopefully that is correct too?)

  • @Clayton,

    yes, this is correct. You can backup your files and insert or remove them to the images folder again.

    I often do this to check the scenery with or without my custom images.


    Ian ,

    aerofly FS 2 uses the world grid system. The maximum number of tiles in each direction is 65536, the starting tile is bottom left.

    So the tile borders don't fit exactly to even coordinates. I published this image for level 4 once before in another thread.

    aerofly coffee party



    Rodeo

  • I am getting this very same thing, kind of annoying. I have a fairly large area done, 100x100nm give or take. The edges seem to not pop in at the higher resolution until I am right on top of them. If anyone figures out why, pass it along. :)


    Also, can we create Level 4 textures and use them to replace the stock ones? One annoying thing is that once I get high enough, I can see off in the distance where my custom scenery has changed to the default. The color is very different. If I could replace a large area with a similar color level 4, it would not be as big of a deal.


    Andrew

  • Yet another question. The more I do this, the more questions keep coming up!


    I've now decided to start with a level 10 tile as a base area and build the other levels on top of that up to level 15. My higher level tiles will be generated from FSET images with a resolution of -1. I'm wondering if there is any point in using FSET images of a lower resolution for the lower level tiles (10, 11 and12)? I understand that the lower level tiles need to be of lower resolution to function properly, but surely they will be of a lower resolution anyway since they are a similar file size to the higher level ones but cover a bigger area? The fact that they are generated from a higher resolution original doesn't affect that - or does it? I can understand that if you were only creating levels 10, 11, 12 it would save time to set FSET to a lower resolution - but since I'm doing the whole area at -1 anyway I might as well use the higher res for the lower levels.

  • You can use the high res images to create the lower res levels. The converter does this for you. And since the pixel size is 2048x2048, the file size is similar. But of course the lower levels cover a larger area. Level 10 is usually omitted while converting levels 9, 11-14. Since you have FSET -1 you can actually go to level 15.


    Btw, did you read my conversation question?


    Rodeo