A first exploration of the increased photos resolutions

arno

Administrator
Staff member
FSDevConf team
Resource contributor
#1
Hi,

Over the last days I have been exploring the usage of the increased photo resolution on the mesh terrain and I would like to share my results with you.

Let me start with the source images I used. I am lucky to have access to some high resolution images (16 cm resolution) of the area around Schiphol airport in the Netherlands. So I used these as a test. I have them in the ECW format, so my first was to convert them to GeoTIFF images. As they are also in the Dutch RD coordinate system, I reprojected them to WGS84 as well when I created the GeoTIFF images. To do all this I used some of the tools of the GDAL library.

Why did I choose the GeoTIFF format? Mainly because it makes placing the images in FS a lot easier afterwards. The GeoTIFF format stores the location of your image in the file as well, so you don't have to tell resample about it anymore. You will see that it makes the INF file a lot simpler.

As my images have a quite high resolution (after the resampling to WGS84 around 20 cm per pixel) and it covers a resonable area as well (about 8x15 km), I had a huge amount of data in the end. So much data that it did not fit in one GeoTIFF file, so I split it into 6 parts. In total about 15 GB of data.

In the INF file for FS you can use multiple sources, so I added all my GeoTIFF files there and let resample do the magic of merging them all. After reprojection of the images, they had a small black border around them (due to the rotation that occured during the reprojection). By setting the null value in the INF file to black, resample nicely took away these pixels and my images joined very well.

Code:
NullValue        = 0, 0, 0
My first go to convert this INF file was not a huge success. After around 8 hours of compilation I had my BGL file. But it was almost 6 GB in size and that is too big for FS to load. If you BGL file is above 2 GB in size it will simply not show in FS. So I had to do another compilation and this time I included the option to split the BGL file automaticall in different files based on the LOD grid. I used the LOD11 in this case to keep the file sizes under 2 GB.

Code:
SplitFileLOD     = 11
So after another 8 hours of compilation I now had a collection of BGL files and they show very well in FS. I must say that I am very happy with how it looks in FS, the textures really show a lot of details (especially if you compare it with the Fs2004 resolution) and that makes the scenery look a lot better. I have attached some screenshots of the result (the JPG compression reduced the quality a little bit) and also the INF file I used as a reference.

On my PC, which is quite new, I also did not see a big reduction in performance from loading this huge amount of data. But when you are flying fast, I don't think the highest resolution is rendered fast enough, so such high resolutions are probably only useful at airports and for VFR flight locations.

As you might have seen on the screenshots (if you have already looked at them :)), I have also tried to tweak the XML scenery of the airport so that the taxiways do not show. I changed their type from TAXI to PATH and that only shows the center and edge lines, but not the concrete/asphalt of the taxiway itself. I still have to explore this idea a bit more, but this might give a nice solution to the problem that a lot of sceneries have with their Fs2002 style high resolution ground polygons and the curvation of the earth. It is still a bit to early to give a real conclusion on this, as I still want to do some more testing. But I think if you clean the aerial photo so that it no longer contains markings, aircraft and other details this could lead to very nice results with the sharp markings from the XML on top. My main worries are that the XML markings might not be flexible enough to make really realistic patterns and also not flexible enough to make red clearance lines for example. But I need to explore that a little more to be sure about that. So to be continued...
 

Attachments

#2
Arno, great work! I hadn't played with null value yet, nice results. I've seen that black line also before.

Now I'm interested in looking at how quality is changed by:

1. Compression in the destination file
2. Reduced resolution vs perceived quality

I have extremely high res imagry myself, and I can post by the weekend some testing to look at this.

Bob
 

arno

Administrator
Staff member
FSDevConf team
Resource contributor
#3
Hi Bob,

I have not changed the default compression for the moment. And I don't think I will test it with the full set of images (don't want to wait 8 hours every time). But it might indeed be interesting to see what effect that can still have.

What exactly do you mean with your second point? I tried to change the display setting that control the maximum displayed resolution and you can very clearly see the effect of that. For example the grass loses a lot of its sharpness if you go to 1 meter resolution.
 
#4
Hi Arno,

just a short question: As far as i know (and some people told me so) using a new resample photoscenery like yours with a mask channel on top of another new resample photoscenery will cause the masked borders to look like water.
Can you confirm this? (I´m afraid of what will happen if I make my airport ground with this method and suddenly someone publishes a new general VFR photoscenery for that area (like Paris CDG and Paris VFR scenery) and both are totally incompatible due to that water issue.

Thorsten
 

arno

Administrator
Staff member
FSDevConf team
Resource contributor
#5
Hi Thorsten,

No, I can not confirm that (yet). From what I have read you can either use a mask to create water or also to have them blend together. But I have not tried it yet. That is still something I should do.
 
#6
Hi Arno, very interesting results. The fact that the terrain can now accept hi-res imagery will eliminate the need to have to flatten the terrain and create a large ground poly (using gmax for example) in order to use high-res photos. I think this is the way to go now.



As you might have seen on the screenshots (if you have already looked at them :)), I have also tried to tweak the XML scenery of the airport so that the taxiways do not show. I changed their type from TAXI to PATH and that only shows the center and edge lines, but not the concrete/asphalt of the taxiway itself. I still have to explore this idea a bit more, but this might give a nice solution to the problem that a lot of sceneries have with their Fs2002 style high resolution ground polygons and the curvation of the earth. It is still a bit to early to give a real conclusion on this, as I still want to do some more testing. But I think if you clean the aerial photo so that it no longer contains markings, aircraft and other details this could lead to very nice results with the sharp markings from the XML on top. My main worries are that the XML markings might not be flexible enough to make really realistic patterns and also not flexible enough to make red clearance lines for example. But I need to explore that a little more to be sure about that. So to be continued...
I still think that that we will end-up overlapping the taxiways with ground polygons, as probably we will never be able to achieve that kind of high-res asphalt, concrete texture etc...... with just aerial photos. Especially since FSX includes bump mapping now. However I'm not sure if this applies to ground polys, so I could be wrong.
To tell you the truth I haven't worked with 15cm/pixel photos but I have worked with 25cm/pixel photos. From the air they look brilliant but when on the ground it was a different story.

Those XML markings seem quite restrictive, even to me. It now seems that the centreline has been changed from yellow to yellow/black. Does anyone know if the color can be changed, coz as far as I know yellow/black is only used on concrete surfaces to create more contrast.

Daniel
 
#7
Arno: When you have time please give this a try:

http://www.flytampa.org/forum/viewtopic.php?t=1862

Scroll to Update 25 Oct.

Compile a 2nd Photoscenery "under" the location of the SDK sample "MillenniumImage_water_blend.bgl". Add both Bgls as separate scenery entries and check results. Notice scenery.cfg layering makes a difference, but neither is acceptable from a high-res airport design perspective.
 

arno

Administrator
Staff member
FSDevConf team
Resource contributor
#8
Hi Daniel,

Especially since FSX includes bump mapping now. However I'm not sure if this applies to ground polys, so I could be wrong.
I still have to check this, but I don't think the bump mapping works on the kind of ground polygons we use. It does work on the XML generated scenery and probably also on the MDL objects. But these last are not really suited for ground polygons (as was the case in Fs2004 as well). So I am still not sure what is the best way to go for the future, it will take some more testing.

Those XML markings seem quite restrictive, even to me. It now seems that the centreline has been changed from yellow to yellow/black. Does anyone know if the color can be changed, coz as far as I know yellow/black is only used on concrete surfaces to create more contrast.
Yes, I also noticed that. I think the only way to change that is by replacing a default texture (which would affect all scenery in the entire sim). My main problem with the XML code is indeed also that it is not flexible enough if you want to make something that does not look like the default scenery.

I am for example also missing the ability to draw red or white lines as markings. These are quite important as well to give your airport the correct atmosphere.
 

arno

Administrator
Staff member
FSDevConf team
Resource contributor
#10
Hi Dan,

No, not yet. I am a bit short in time at the moment. So I haven't had to chance yet to do more playing with the new techniques.
 
Top