GUI based Photorealistic Condor Scenery Tutorial - draft

Everything related to creation of new sceneries for Condor...

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Andy1248
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Re: GUI based Photorealistic Condor Scenery Tutorial - draft

Postby Andy1248 » Sat Apr 29, 2017 10:07 pm

Wow! fast reply. Thanks Tom, I will try that.

That worked Ok and I now have calibration points data.

One more question;

How do I save the SS so that I can access it with the scenery data again?
Condor CN = E20

luisbriones
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Re: GUI based Photorealistic Condor Scenery Tutorial - draft

Postby luisbriones » Tue May 02, 2017 2:15 am

Hi Tom,

I tried to follow your tutorial but I not understand someting.

When you use 3DEM you don't convert the file to UTM at this moment. I didn't find that you made that conversion at all. Maybe it my mistake because is not easy reading English to me.

With no convertion and using your calibration data from your spreashet, the distance between wp is incorrect

I don't know if I lost something when I read or have another mistake.

BTW, I try to use the SAS.Planet program to obtain satellites images

Regards,

Luis

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Jan Oorthuijsen
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Re: GUI based Photorealistic Condor Scenery Tutorial - draft

Postby Jan Oorthuijsen » Tue May 02, 2017 8:34 am

Hi luis,

Read my questions page 3 and 4.

Grts, Jan
PH-722
WW
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tberry
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Re: GUI based Photorealistic Condor Scenery Tutorial - draft

Postby tberry » Wed May 03, 2017 1:04 am

"How do I save the SS so that I can access it with the scenery data again?"

The spreadsheet is a template. When you open it, you will get a Google Sheets file that is yours. Here is more info: https://support.google.com/docs/answer/148833?co=GENIE.Platform%3DDesktop&hl=en

tberry
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Re: GUI based Photorealistic Condor Scenery Tutorial - draft

Postby tberry » Wed May 03, 2017 1:04 am

"With no convertion and using your calibration data from your spreashet, the distance between wp is incorrect"

Luis, the SRTM data is already in UTM format. As Jan notes we discussed this on pages 3/4 of this thread. Are you at a high latitude?

After much investigation, I have concluded that this distortion is the result of Condor's method for creating scenery. The scenery is represented as a grid of pixels and those pixels are assigned a certain size. Because the grid is square and latitude lines are NOT square, this distortion is inherent in the method for scenery creation and it becomes more apparent the closer one gets to either pole.

I believe the source of this is the SRTM data and it is the reason that NASA does not supply SRTM data near the poles - the distortion is too great.

luisbriones
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Re: GUI based Photorealistic Condor Scenery Tutorial - draft

Postby luisbriones » Wed May 03, 2017 2:29 am

Jan Oorthuijsen wrote:Hi luis,

Read my questions page 3 and 4.

Grts, Jan


Thanks Jan for your anwser. I read it. The problem is complex. I'm lost!!! :-)

luisbriones
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Re: GUI based Photorealistic Condor Scenery Tutorial - draft

Postby luisbriones » Wed May 03, 2017 2:48 am

tberry wrote:"With no convertion and using your calibration data from your spreashet, the distance between wp is incorrect"

Luis, the SRTM data is already in UTM format. As Jan notes we discussed this on pages 3/4 of this thread. Are you at a high latitude?

After much investigation, I have concluded that this distortion is the result of Condor's method for creating scenery. The scenery is represented as a grid of pixels and those pixels are assigned a certain size. Because the grid is square and latitude lines are NOT square, this distortion is inherent in the method for scenery creation and it becomes more apparent the closer one gets to either pole.

I believe the source of this is the SRTM data and it is the reason that NASA does not supply SRTM data near the poles - the distortion is too great.


My airport is at -39º, -67.62º. I'm closer to equator than you :-)

That are my data in the sreadsheet:

Code: Select all

Input data      
      
                  Longitude (X)   Latitude (Y)
Desired scenery center pont   -67.62000000   -39.00000000
                  Width (X)   Height (Y)
Desired scenery size in terragens   10   14

Scenery clipping details   Point 1 (upper left)   Point 2 (lower right)
            X   -68.68662400   -66.55337600
            Y   -37.50672640   -40.49327360


My reference wp is S38°59'21", W067°17'25". It's 50.8km away to my airport to the east. All my wp and airport look good in map, but east-west distance are incorrect

task.jpg
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luisbriones
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Re: GUI based Photorealistic Condor Scenery Tutorial - draft

Postby luisbriones » Wed May 03, 2017 2:45 pm

I was thinking about the problem and made the following test.
I used excel calibration tools from Lurik and made a new calibration point file. For clarity I only used 4 values (Cells L43 to L45)

0,0,-40.56582186,-66.18171986
230400,0,-40.60023145,-68.90325931
230400,322560,-37.6936068,-68.90715888
0,322560,-37.66256638,-66.29515128

Now the distance is correct as you can see here:

task-1.jpg


Is not a good calibration, all point are displace to north of it real position

I put both calibration files in QGIS, with one of my geotiff images tha I made with SAS.Planet program

QGIS.jpg


I don't know how follow from here. I'll do more test, but any help will be apreciated.
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luisbriones
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Re: GUI based Photorealistic Condor Scenery Tutorial - draft

Postby luisbriones » Wed May 03, 2017 3:42 pm

Jan Oorthuijsen wrote:Hi Luis

Where is the conversion to the correct UTM projection ?,was my question a few years ago.
Now I know that in Qgis you need to do the conversion through, Raster> Projections> Warp (reproject).
 And than Cut with ,Raster> Extraction> Correct Clipper (Multiple of23040m ) .
Did not get a correct answer and therefore I stopped follow that tutorial.

Do not forget to correct the size (look in hdr file) by -45 m and + 50 m , If you follow the old method
Search the forum for this.

Grts, WW


Jan, I move my answer here, because I think that this discussion is better make in this post.

In what part of the tutorial do you have to do the conversion and the cut?

Sorry about that silly question, but I tested many thing and I a little (big!!!) confused now.

I tried to follow the another method to make a photorealistic scenery, but I have troubles too. I'll write about it in the proper post.

tberry
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Re: GUI based Photorealistic Condor Scenery Tutorial - draft

Postby tberry » Wed May 03, 2017 8:03 pm

Now I see. It does look like the calibration points tab is incorrect. I'll take a look at that and see if it is obvious what is wrong.

I suspect it has something to do with the southern hemisphere location. I originally built the spreadsheet for U.S. locations, then added southern hemisphere adjustments to it. As far as I know, it hasn't been used for that yet and I may not have thought it through completely. Sorry about that.

tberry
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Re: GUI based Photorealistic Condor Scenery Tutorial - draft

Postby tberry » Wed May 03, 2017 8:22 pm

@luisbriones:
In what part of the tutorial do you have to do the conversion and the cut?

The reprojection is done at the end of the tutorial. The tutorial uses images in EPSG:3857 projection and reprojects them to EPSG:4326 (Condor) in the step prior to cutting the full mosaic.

luisbriones
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Re: GUI based Photorealistic Condor Scenery Tutorial - draft

Postby luisbriones » Wed May 03, 2017 9:27 pm

tberry wrote:@luisbriones:
In what part of the tutorial do you have to do the conversion and the cut?

The reprojection is done at the end of the tutorial. The tutorial uses images in EPSG:3857 projection and reprojects them to EPSG:4326 (Condor) in the step prior to cutting the full mosaic.


I saw this and always had a dude about it. You say EPSG:4326. I understand that is WGS84. Does Condor not work on UTM?

By the way, I have partial success to make the images using P. Strzelec method. You are part of this success, because I learned QGIS from your tutorial. It's not finish yet, but look good.

Anyway if you wish I can help you to fixed your spreadsheet problems

tberry
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Re: GUI based Photorealistic Condor Scenery Tutorial - draft

Postby tberry » Wed May 03, 2017 11:57 pm

I don't know how follow from here. I'll do more test, but any help will be apreciated.

I calculated the corner points by hand and came out with the same answer as the spreadsheet. Before we can figure out if there is a calibration error, I want to make sure I can at least get the same corner points as you did with Lurik's spreadsheet.

Let us check a few things first. To make sure I understand:

1. The RED dots are the corners from my spreadsheet. The BLUE dots are the calibration points from Lurik's Excel spreadsheet, correct?

On my Google spreadsheet:
2. What number is in cells J16 and K16?
3. What number is in cells E24 and E25?

The reason I ask is that the width of the scenery is calculated mathematically and is based on values in those cells. Here's how it works:

-Each pixel of the SRTM data represents 90 meters. When you use Raster->Misc->Info on the SRTM data, it gives you the pixel size in decimal degrees and that number should be in cells E24 and E25 (it is the same for both width and height).
-Each terragen tile is 256 pixels of SRTM data. So, a terragen tile is 90meters X 256 pixels = 23,040 meters in width.
-Your scenery is 10 terragen tiles in width, so 23,040 X 10 = 230,400 meters in width. You may notice this value in the calibration points you posted.
-230,400 meters X the value in E24 (pixel size in decimal degrees) = width of the scenery across those 10 terragen tiles in decimal degrees.

I calculate the width of your scenery to be 2.133248 decimal degrees. The values you posted show it to be 2.72153945 degrees, which is slightly wider than I calculated.

I use that width to figure out the upper left, upper right, lower right, lower left corners of the scenery. If the pixel size in E24/E25 is changed, this would introduce an error in the size.

I still think there's probably an issue with shifting everything north, but first I wanted to figure out the correct corners.

luisbriones
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Re: GUI based Photorealistic Condor Scenery Tutorial - draft

Postby luisbriones » Thu May 04, 2017 12:24 am

tberry wrote:1. The RED dots are the corners from my spreadsheet. The BLUE dots are the calibration points from Lurik's Excel spreadsheet, correct?


No. The RED are from Lurik and BLUE are yours

tberry wrote:On my Google spreadsheet:
2. What number is in cells J16 and K16?

0.2133248 0.2133248
tberry wrote:3. What number is in cells E24 and E25?

0.0008333
0.0008333

I send you screen captures from the spreadsheet and the calibration point generated by then.

S-1.jpg

S-2.jpg

S-3.jpg


Code: Select all

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0   0   -40.49327469   -66.55337524
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tberry
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Re: GUI based Photorealistic Condor Scenery Tutorial - draft

Postby tberry » Thu May 04, 2017 12:54 am

The obvious difference is that Lurik's calculations use a larger pixel size.

If you subtract his upper left corner from the upper right corner, you get: 68.903259310-066.181719860 = 2.72153945 degrees width for 10 terragen tiles.
That means each terragen tile in the 10 row width is 2.72153945 / 10 = .272153945 degrees wide.

If you divide that width by 256 (the number of pixels per terragen tile):.272153945 / 256 = .0010631013476563 <--value for cells E24/E25

My value is smaller (0.0008333) and comes from the SRTM data. Thus, the difference between the two spreadsheets.

What I'm having difficulty figuring out is why my calibration points, which are CLOSER together would make distances on your flight planner to be FARTHER apart than Lurik's calculation. I would expect the opposite to be true. Are you SURE that you didn't accidentally use Lurik's calibration points in the flight planner example you posted?

Out of curiousity, what technique are you using to cut the imagery tiles and where are you getting the numbers to cut them from?


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