Sign in to follow this  
Guest JohnC

Google Eath and photo scenery

Recommended Posts

I am wondering if anyone has compiled a tutorial on creating photoscenery from google earth for FSX. I have been keen to create my own photoscenery for a while but now that FSX supports such great resolution I was going to try and start my own project. Anyone got any ideas where to start. I have looked in the beginners post but there isn't much info on FSX and I am not sure what stuff still applies to the FSX SDK? Any pointers or help appreciated..CheersSteve

Share this post


Link to post
Share on other sites
Help AVSIM continue to serve you!
Please donate today!

Hello Steve,Sorry, we'll get around to a new FSX Beginner's Guide as soon as I get over the Christmas hangovers (some parties!).In the meantime, Bob Bernstein is our expert on custom ground and hopefully he will step in and provide guidance.Best regards.Luis

Share this post


Link to post
Share on other sites

Thanks Luis, looking forward to some input from Bob..Steve>Hello Steve,>>Sorry, we'll get around to a new FSX Beginner's Guide as soon>as I get over the Christmas hangovers (some parties!).>>In the meantime, Bob Bernstein is our expert on custom ground>and hopefully he will step in and provide guidance.>>>Best regards.>>Luis

Share this post


Link to post
Share on other sites

Hi all, Steve, the steps to create custom ground involves capturing and manipulating your imagry, and then compiling into bgl.I don't use Google Earth for anything, so I'm no expert with their images. But I imagine them to be simply an image source, so generically, you capture the image however you can, preferrably downloading the image in a way that captures its metadata and preserves its resolution...metadata reports the files geographic boundaries, and its projection.If your image downloads in "geographic" projection, perhaps it will be called "geodetic", and if your image references wgs84 datum, then you will be already set to go. If not, you need to convert the projection and datum. I can't explain the conversion process here using freeware tools, I've become spoiled. I bought a license of Global Mapper for that, which is a commercial gis tool. (about $250). There was at one time a great avsim thread on using freeware tools, search the forum for that thread).Once you have your image in the correct projection, and know the geographic boundaries, you create a text file called the inf file. This can be done in any text editor, including notepad.Review the fsx terrain sdk. There are explanations of the inf file structure and you can do some cut and paste to shortcut your first effort. You'll of course need the tools for compiling your inf also from the sdk, resample.exe primarily.work on these steps and get back on the forum with questions, that's imho the best way to learn this stuff....try some things and discuss what went wrong.You'll see discussion in the sdk about water/land masks and blend layers, this is some of the fun part, but I suggest you master the steps to get a basic layer to display and get comfortable one step at a time.Enjoy!B

Share this post


Link to post
Share on other sites

Hi Bob, thanks for the notes and helpful comment. Basically what I am planning to do is just use google earth to capture screenshots of a small area I want converted. So I will need to stitch some shots together in photoshop before converting them. I'm not sure if I can download the file with meta data but I can get a grid ref of particular points through google earth. This is probably the thing I find most confusing how to sort out grid refs etc. as I think I read that FS has a different type of ref is that correct? I am assuming that these images are also ortho corrected because google overlays a map on the arial imagary? The projection thing I am unsure about?I will have a look at the SDK a bit further. It's a little confusing to a newbie like myself. I will maybe post my first efforts here.ThanksSteve

Share this post


Link to post
Share on other sites

I'll be on travel til Friday, I'll check in then. I'm sure others on this board know google earth better than I do, and could advise you on projection issues.Best of luck,Bob

Share this post


Link to post
Share on other sites

Hi Luis, thanks for that! This looks real interesting. I managed, before I read your post, to add a chunck of photoscenery into FSX. The coordinates were out by about 20 miles long and around 1 lat. I am assuming this is to do with the difference in coord system between fsx and google. The other thing I noticed was the image had been stretched? A projection issue I suspect..Still learning here but I was glad I actually managed to get something into FSX. I notice this program SBuilder for FSX looks good... will have to try that this evening..Thanks for your help, it is much appreciated..Steve

Share this post


Link to post
Share on other sites

Hi Steve,The images from GE Maps use the Mercator projection while FS uses the geographic (latlon) projection. This means that there will be a misalignement in the NS direction. If you make a photoscenery of, say 1 tile extent in the NS direction, there will be almost no distortion. But if you span many tiles in the NS direction, say 1 degree of latitude, there will be some distortion in the center (not on the north and south borders if your inf and picture are correctly implemented). This distortion becomes worst as you approach the poles.Therefore I would certainly divide your photo project in many "horizontal strips" to avoid projection issues.Regards, Luis

Share this post


Link to post
Share on other sites

Hi Luis,Thanks for your helpful comments, will bear this in mind. Does SBuilder produce corrected scenery?When you say 1 tile are you speaking about the grid on the mercator projection that is shown in the GE app?Steve

Share this post


Link to post
Share on other sites

Hello,SBuilder for FS2004 can produce photoscenery (the link that I passed to you helps on that task). It places the photoscenery as VTP polygons. So you can put other VTP items (polygons or lines/roads) on top of the scenery. You can also place autogen on top of the photo scenery.If you use the Resample tool you can not do that. But the "VTP method" has a problem - the alignement of the VTP photo squares is not perfect on some views and, some times you see small gaps. If you search this forum with the keywords: "VTP" and "gaps" you should get more information on this.A tile is the minimal rectangle that you can cover with photoscenery. It is about 1.2 km by 1.2 km at my home latitude (40 N). If you install SBuilder you can see this tile grid by chosing LOD13 (SBuilder 206) or QMID15 (SBuilder for FSX).Note that SBuilder for FSX can not (yet) place photo scenery. If I had a permission by "Live Earth" to use their image servers, Sbuilder could make the photoscenery in 2 or 3 clicks. Kind Regards, Luis

Share this post


Link to post
Share on other sites

Hi Luis,Ok, I'm beginning to get a picture in my mind of what is and what is not possible. Is it better to use live earth images rather than google earth or are they just the same in terms of projection?Sorry for all the questions, really want to nail this one.. if i can:-) Steve

Share this post


Link to post
Share on other sites

Hi,The projections are the same (Mercator). The coverage is different and, probably, GE is better. I only referred to LE because I do not think that GE would allow me to release a freeware tool to transform their photos into BGL sceneries. Because LE and FS come from the same company, may be they could agree. But this is just my wish :-)Luis

Share this post


Link to post
Share on other sites

Hi Steve....a few hints in using GE......1. Make sure terrain is unchecked in your primary database layers and set terrain quality to highest in options.2. Set your altitude to 2000 feet by trial and error back and forth and once you get there place a placemark there called alt2000.3. Make the yellow pushpin placemark and its label 100% transparent. Now you can return to 2000 feet quickly from now on by clicking on the placemark in your list of places..4. After picture is downloaded and sharp capture image to clipboard by pressing Alt-CTRL-C.5. Switch to Photoshop and store the image.6. Scroll and repeat 4 and 5 until you have about 300 megs if your ram is 1 g. Use the SDK to guide you with using resample.7. Last time I looked in the google forum GeoTiff was not available without huge investment in Google Earth Pro and other support software.8. That is not a problem because you can determine the extents of the pixel in the NW corner of your image, and your pixel size in degrees very easily and place them in resample.Good luck. Using this method I can see rows of headstones in a graveyard, individiual shrubs and the grass between sidewalks and street. Incredible. Long horizontal strips are a real good idea if you have large excursions NS. Google will be very unhappy if you distribute their images.

Share this post


Link to post
Share on other sites

What I have done is to use a utility (such is common in graphics software) to determine accurately screen pixels / inch for my display and resolution. Then, assuming I want 4.8 m/pixel scenery I just compute the distance of meters per 1 inch of screen space. you could also do it for 2.4 or 1.2m. for example 96 pixels / inch x 4.8m/pixel or 460m / inch. In GE (I'm still on ver 3) then use the measure tool to create a 460 m line. Use a ruler and zoom in/out until the line measures exactly 1" on the screen. This should minimize the amount of resampling required of your source data. I use GIS software, so I take a capture with the lat/long grid on and off. Using the grid I georeference the image, then just substitute the identical dimension image without the grid.Once I have my image I create 2 copies or layers in graphics software and go over the copies as necessary to create the blend and watermask images. I send all 3 to resample, plus any night time or winter variations.I think it might be better to set specific output resolutions desired rather than using the default "all". Also try using compression of 90 and see if that helps filesize. right now I am experimenting with 1.2 resolution source data and setting the output LOD to 13,15 to create 4.8, 2.4, and 1.2 m resolution variants. I'm also wondering about total file size and I have been experimenting with the SplitFileLOD to create LOD13 tiles, like in FS9.scott s..

Share this post


Link to post
Share on other sites

Thanks Scott and John C, here is where I am at at the moment. Last night I spent about 3 hours trying to figure out a conversion for the mercator to geographic projection latlon. Here are a few questions:1. How do I convert the lat/long position google earth gives me to the latlon resample requires? My scenery ends up about 20 miles out on the lon and around 1/2 mile out on lat?2. I'm not getting my head around the pixel/meter issue. Is there anyway to work out the pixel/meter by how far you are above the earth in GE.. something like 200m = 2m/pixel3. JohnC when you mention this: "8. That is not a problem because you can determine the extents of the pixel in the NW corner of your image, and your pixel size in degrees very easily and place them in resample." What do you mean by pixel size in degrees? How can you work that out? Do you use the GE app that Luis mentioned above at ptsim?Sorry if I am missing the obvious... keep with me guys I think I am getting there (very slowly!)Cheers,Steve

Share this post


Link to post
Share on other sites

Hello Steve,Here are some answers:1) the lat/lon positions that Google Earth gives are the ones that resample needs (see below). If your scenery is only 1/2 in lat I think that the reprojection is not necessary2) about "pixel per meter" here is what I think - say that you have a picture that spans 1 minute latitude per 1 minute of longitude. This picture spans about 1850 meters in the NS direction (1 minute of latitude is about 1 nautical mile or 1850 meters if I remember). The span in meters in the EW direction depends on the latitude. For a latitude of 40 degres the span is given, approximately by:Span_EW = Span_NW x cos (latitude)So, for a picture with a width of 1 degree of longitude, the span will be, more or less, 1417 meters.Now you, depending on the Zoom settings that 1deg x 1deg picture can have, say, the following sizes in pixels (height x width):case A 200 x 150case B 400 x 300 case C 800 x 600case D 1600 x 1200The resolution of your picture in meters per pixel will be:case A 9.2 x 9.4 ( 9.2 = 1850 / 200 and 9.4 = 1417 / 150 ) case B 4.6 x 4.7 ...case C 2.3 x 2.3case D 1.1 x 1.2If you are using FS2004 resample will produce bitmaps, that you will see in the sim, with a resolution about 4.8 x 4.8 meters per pixel. Therefore you can say:case A - the original picture has insuficient resolution. The resample tool will use interpolation to create the necessary pixels. The produced bitmaps will have about 4 times the number of pixels of the original picture. The final pictures will have a great extent of interpolation and they tend to be smooth and detail is lostcase B - the resample tool only needs to make small adjustments. Probably it preserves the information of the originalcase C - if the resample tool is in line with the "sampling theory" this seems to be the best input in the sense that ... case D - ... you can not preserve the detail of this picture in the output image. Probably you are loading your system with unnecessary data; processing time is longer. 3) You need to specify the following parameters in the INF file required by the resample tool: Lat = Lon = NumOfCellsPerLine = NumOfLines = CellXdimensionDeg = CellYdimensionDeg =The web tool that I pointed out to you shows the borders of a picture. If you do not use that web tool you should be able to get these borders. Say that they are:North < north border latitudeSouth < north border latitudeWest < west border longitudeEast < east border longitudeSay that your picture has a height and a width in pixels of:Rows < height in pixelsCols < width in pixelsThe formulae for the INF are: Lat = North Lon = West NumOfCellsPerLine = Cols NumOfLines = Rows CellXdimensionDeg = ( East - West ) / Cols CellYdimensionDeg = ( North - South ) / RowsA final note about the reprojection - if you go from Mercator to LatLon or viceversa, longitudes "do not change". So we are only worried about latitudes. The north border latitude that the INF file sends to Resample is OK (you read it from a chart or else). The CellYdimensionDeg parameter will allow Resample to walk on the input picture with minimal error if the the vertical span is low.I hope this is correct and useful,Regards, Luis

Share this post


Link to post
Share on other sites

hELLO STEVE... OPEN UP GE AND CLICK ON TOOLS AND GOOGLE EARTH OPTIONS WILL ALLOW YOU TO SET THE LAT/LONS IN dEGREES "ONLY".NOW YOU CAN FIND THE nORTH AND SOUTH LATITUDES AND EAST AND WEST LONGITUDES IN DECIMAL DEGREES OF YOUR BITMAP. cLICK ON vIEW AND MAKE SURE STATUS BAR IS CHECKED...IT WILL APPEAR AT THE BOTTOM AND WILL HAVE YOUR LAT LON EXTENTS IN DECIMAL DEGREES....HOWEVER, INSTEAD OF MOVING YOUR CURSOR AROUND AND WRITING DOWN NUMBERS...........YOU CAN GET PRECISE VALUES AND KEEP THEM FOR FURTHER REFERENCE IF YOU PUT PLACEMARKS PRECISELY ON THE nw CORNER AND se CORNER OF YOUR IMAGE. tHE PROPERTIES DIALOG BOX WILL STORE THE EXACT COORDINATES IF YOU NEED THEM LATER. YOU'LL GET THERE.

Share this post


Link to post
Share on other sites

I have been struggling to create an airfield using GE, not so much getting the shot but trying to figure out the optimum height. I have tried 200m which took about 12 different shots which I painstakingly put together in photoshop. However despite all of that, whilst it looks great from the top down view, even as I zoom in, however the moment I am in spot view it is just mushy, no detail at all. I have tried putting a small texture on but that hasn't made a fat lot of difference.Also I have been using the Gmax FS2002 gamepack to cretae a ground polygon, however whilst I can get everything in the right place, if I use DXT5 with an Alpha to get a nice blend, the Aircraft shadow dissapears in one part of the airfield, despite no height change, if I use DXT1 and colourkey, no problem , the shadow is on wherever the aircraft is, trouble is I get that horrible black edge.Don't suppose anyone has any pointers or ideasThanksPaul

Share this post


Link to post
Share on other sites

Guys, I have done it! Thank you Ruis for all your help and to johnC. After hours of mucking around with numbers I managed to create a strip of imagary around my airport which matches 100%. I am now totally impressed with this.. ok must go and grab a beer! :-jumpy Cheers guys!Steve

Share this post


Link to post
Share on other sites

Well, maybe I shouldn't be drinking my beer so fast. I have run into problems. After trying to add my second bgl with a water mask I am getting strange water squares appearing all around my nice new textures :-( I didn't think this was going to be easy..help anyone?Steve

Share this post


Link to post
Share on other sites

Show us the squares and tell us whether you used an blend mask and/or a landwater mask and publish your inf file. BTW, You will soon develop an irresistable urge to post a few screenshots in the AVSIM screenshot forum

Share this post


Link to post
Share on other sites

Hi JohnC,I don't have the files here (at work, well supposed to be!) I did use a landwater mask but then tried without the land water mask and the same problem appeared? I had 2 texture strips running horizontaly. One set had a SW coord of 56.4556 and the NW coord for the next strip the same. Should I overlap slightly when creating textures?Steve

Share this post


Link to post
Share on other sites

Hello,The row of tiles that are traversed (spelling?) by that common border will not be generated. I think that there is "multisource" type of parameter and I do not now if you can instruct the resampler to "glue" the 2 source pictures. Regards, Luis

Share this post


Link to post
Share on other sites

Steve, congrats on your progress. Make sure you've downloaded the sdk update off the ms insider site for photoscenery. The update fixed some bugs that sound similar to what you are seeing.You can include each image as additional sources in your inf file, and compile them all into one bgl. The sdk describes that.Best,Bob

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this