Re-sizing Pictures

[Guest]

I am trying to do some scenery using pictures I have from the NetThe size are 8000 x 6000 pixels at 2.5 meters per pixelHow do I re-size them to get the correct 4.75m/pixelI have tried one way I have been told and it works out OK when Iput the pictures into Terrabuilder but my problem is thenthey don't seem to cover the correct area.If I ancher the textures at one point which is correct, then aftermoving from say S 43:35:36 E171:31:54 to S 43:45:00 E 172:0:0:it is to small by about S 00:00:22:2 sec in the N/S and aboutE 00:00:32:4 in the W/E so it ends up not covering to the correctareaThanks

[toprob 105]

NormanAre you working on the new colour images from the LINZ site? These cover about 40x30kms, so it is difficult to get them to line up with everything in the flightsim world, especially if you want the coastline to fit. I've got a good fit for Taranaki using a rough 2.5 to 4.8 conversion, but the Napier/Hastings one is causing problems -- if I resize it to line up on Napier and Hastings airports I have to squash the image by about 8%. At least I have two FS reference points here to help me use Terrabuilder's two-point calibration, but this isn't the complete answer. There is quite a bit of massaging to make it all work. When it does work well -- such as having the rivers precisely follow the shape of the valleys -- it is truly amazing.One thing I've tried is to use the two-point callibration method to obtain the new mpp values, and use these to resize the image in photoshop. This means that my slightly squished image doesn't need to be resized using the resampler, which still does a poor job from what I've seen today.What are you working on, just for interest's sake ? :)-Robin

[Guest]

RobinNo I am working still with the older B/W ones from LINZI am working on the area from North of the Rangitata River to the Rakaia River and inland to Darfield.I have joined the area's of L36 a,b,c,d and L37 a,b,c,d all togetheras one picture, and am using the Airfield at Pudding Hill as the mainreference to line up with the hills But by the time I get down to Ashburton , the Airport there is out by about 1 1/2 times it's widthto far to the North/East Cheers Norman

[toprob 105]

You could try the two-point calibration -- I would get the values from FS2002, calibrate using Terrabuilder then divide 4.8 by the value of each (horizontal and vertical) resolution (m/pix). This would give you the percentage to adjust your image in your imaging software. You may need to adjust the horizontal and vertical independently to get your two airfields to line up.Unfortunately this method is not too accurate unless there is a fair amount of separation both horizontally and vertically. Be prepared to experiment!The best I can normally manage is two airports lined up, one end of the coast but the other end of coast way the hell out of whack...

[toprob 105]

I've been experimenting, and what I've suggested here just doesn't make sense -- there's nothing wrong with the scale of the images I'm making (after resizing by 52%), the images actually need to be rotated! I've just recompiled Napier/Hastings, and I get an exact match rotating left 2.15 degrees. I'll try this on other LINZ images -- maybe that'll work for them all.

[Guest christian]

Norman and Robin,The LINZ photos aren't georeferenced and I would expect all sorts of trouble. What you really have to do is buy some expensive software, get the LINZ topographical database and match the photos to the topographical dataset. Of course that's not really feasable. I have both software and data, but it's quite a big job and I don't have the time to do it...In conclusion, you just have to live with the fact that the photos won't match 100%...Robin, using scaling and rotation you should be able to get a reasonable fit. What I nightmare working out the correct parameters though. Maybe if you ask LINZ they will give you the corner coordinates of the images?Cheers, Christian

[Guest]

Robin and ChristianThanks for confirming what I thought.That's going to make it really hard because I am using 17 LINZ photos put together into 4 big pictures to coverthe area.It will nearly make it impossable to join them together as partswill be missing unles I'm missing something.Cheers Norman

[toprob 105]

Ok, today I've taken the day off because of the flu, so I've spent all day on this. I did plan to get it out of the way by 10am, then start a new GMAX tutorial, but this is real fiddly work.I've redone the Taranaki area using the same technique as above:Resized 4 LINZ images to 52%, combined them into one;Colour-corrected and tidied up;Rotated left 2.15 degrees.Used Terrabuilder to calibrate on one single point -- for Taranaki I used the summit, just by flying over it and reading the coordinates. For Napier I took the values from the runway.Had to enter the resolution of 4.8 manually as sometimes it resized the image -- dunno why.The results are great -- by the time i get to Hastings airport I'm about 10 metres out -- easily fixed. Mt Taranaki looks a lot better with more precise lineup of the texture :)Take a look at the screenshot of Taranaki:http://www.windowlight.co.nz/ontarget/FSscreen03.htmlThere's also a rough shot of Napier (not the final placing, but close enough.)http://www.windowlight.co.nz/ontarget/FSscreen18.html

[Guest]

Looking good. Makes a big difference to Mt Taranaki also Napier.I have been thinking about it and will have a play tomorrowIf I only had one picture it would not be to bad, butwith having 5 it makes it a bit hard because I have not gotthat many ref points but only those at each 15 min Degreesso I don't realy know untill I have layed out the whole 5 pictureswill I know if I have it correct.I tried joining more pictures together but not enought Memoryas I only have 768 Meg . Can't afford any more.Cheers Norman

[Guest christian]

I dunno if you are in kiwiflightsim, so I just post this here, because that should be of interest to you both. Original post from Jamie, relpy from me:Thanks, Jamie. I didn't know you can actually see the trigs in the photos. That's a very good idea. I even have the trig data which makes it even easier.You raised a really ugly point. The photos are probably in NZMG, so they will have to be completely skewed to fit to WGS84. The textures really have to be run through some image registration software, I guess :(Cheers, Christian--- In kiwiflightsim@y..., "Jamie Marshall" wrote:> OK - time for surveyor input - we love coordinates and image overlays :-)> > Go back to LINZ! On their web site there is a search for trig coordinates. Most of the trigs shown on the NZMS maps have a name which can be enetered into the search database and will spit out the answer in New Zealand Geodetic Datum 2000.> > http://www.linz.govt.nz/rcs/linz/pub/web/r...abase/index.jsp> > Once you have this information you can enter any of the data into the LINZ Coordinate conversion page which will give you the answer in WGS84.> > http://www.linz.govt.nz/rcs/linz/pub/web/r...sions/index.jsp> > Very long winded but will give you pretty good coordinates. > > I also have a series of programs from LINZ that will do the coordinate transformation from NZMG directly to WGS84 by using data in/out files.> > Now the hard part of all of this is to overlay the image to the correct coordinates. The black and white LINZ orthophotos are about 2m pixel resolution but it is possible to see the the 8m high trigs (black triangles in the NZMS maps) on top of clear hills. I have done a 'double overlay' method previously getting the NZMS map scans to the right scale and marking features on it, removing the nzms and then matching the same features on the orthophoto overlays.> > I hope this has been of some help to someone,> > Jamie Marshall

[Guest]

Thanks Christian and yes I had seen it on KiwiflightsimBut am not posting their at the present time CheersNorman