Geo-reffing tutorial
polycounter lvl 15
This is more to get people pointed in the right direction. Hopefully someone finds it useful.
So one cool thing about game art creation is that there can be specialized things that pop up. Those of you in dealing with Military sims and racing sims have dealt with this at some point in your life. Most tutorials on taking sat images (color and height) are for pre-rendered only. So let's just get right to it.
This stuff is soooo specialized, that the tools are kinda expensive. There are free alternatives, but usually I am asked to align things which these free tools don't do, they just convert. You can find data that is already aligned and set to go though. I won't go into aligning geospacial images with height data, that in itself is a tutorial...
But really quick on alignment, you need to know your long and lats and degrees and minutes, your global position and you height and planar values. From there you tell the software that this long and lat is this, and on the other image this is the same point. The more points you geo ref, the more aligned it will be. Images are warped from camera lens and atmosphere, along with lasers bouncing off random crap(shimmering water, trees, boats, and other stuff).
You will need:
So you got your color info in, and you have your height data. My first order of business is to make sure that the height data is cleaned. So start by importing your height data into Photoshop. Then bring in the color info and plop it on top of the height data. I make sure to work in 16bit color mode. So from here you use the color info (that is aligned) to check your work as you paint out all the man made things.
It's a loooooong riverway. If you do not need to go underwater, then don't worry about it,just make sure it's consistent. As for the edges, try and match then if you are aligning images. If you are having trouble with the banks, take a look at the trees and how they grow. They give hints on areas where you can't see.
I sample the greyscale data A LOT, and then paint. Painting out a clump of trees for instance, I sample a few points around the clump and paint it out, so the height data won't be perfectly flat. For roadways and such, I don't sample as much to keep it straight. Same for parking lots. Riverways, I sample the deepest point for a section and work my way up. For golf courses, I sample kinda deep, then make all waterways the same depth (this is for the water plane in game engines). Houses, I use the same technique for trees, but I sample OUTSIDE the house lot area. My goal is to try and paint things out to a point before people made stuff on it (minus man-made waterways). So you do this ALL over the image. For each type I am masking out, I add a layer, for instance: waterways, houses, concrete, buildings and so on. From there you load into your 3D app of choice and check the data.
I would imagine for racing sims, the initial tarmac data is removed, then you go in with separate data of the grading, pitch and bank from the track itself and put that geometry on top of the terrain height data. So you'd want to make sure the elevations under/around the track are good.
You are looking for spikes from missed pixels and such. This is VERY important for golf sims. Actually, when it's for a golf sim, or golf course pre-vis you have to look at contour data as well.
The grey looks the same, but it's not, there is a slight grade from south to north. Also sometimes the natural environment will dictate how you tackle things, I can't teach that, it all comes from experience.
Now for the color map. There's many different ways to do it. Depending on what is asked I may clean up the image or I may not. And if they ask to have the image cleaned below are the techniques I use and what types they belong to.
Complete clean All man-made and ground foliage minus grass is removed. Also, you have to look for all the stitching from the imagery. This is used for golf games, videos and ground based sims. I sample larger areas and use a lot of cloning brush. Then I make masks of the area types to reduce the "Hey you used the clone brush" look by bringing in low and high frequency texture data. I bring back all the data and export what they asked for.
Partial Clean I remove man-made stuff of a certain height. This is used for flight sims.
Shadow clean Annoying, but I go in and remove all the shadows from almost everything.
No clean Just for map data usually.
So as you work, save and save often. I also save in *.PSB format when working in Photoshop. Hopefully this will get you looking into other avenues for work in these difficult times. As no one likes cleaning this kind of data!! Whatever you do, don't rush it, as these companies will keep coming back if you put out solid data with a good turn around.
Another thing to look into is the next round of GPS software will be making use of 3D objects to represent real-world locations. Companies are looking for artist.
Hugs and Kisses,
Lamont
So one cool thing about game art creation is that there can be specialized things that pop up. Those of you in dealing with Military sims and racing sims have dealt with this at some point in your life. Most tutorials on taking sat images (color and height) are for pre-rendered only. So let's just get right to it.
This stuff is soooo specialized, that the tools are kinda expensive. There are free alternatives, but usually I am asked to align things which these free tools don't do, they just convert. You can find data that is already aligned and set to go though. I won't go into aligning geospacial images with height data, that in itself is a tutorial...
But really quick on alignment, you need to know your long and lats and degrees and minutes, your global position and you height and planar values. From there you tell the software that this long and lat is this, and on the other image this is the same point. The more points you geo ref, the more aligned it will be. Images are warped from camera lens and atmosphere, along with lasers bouncing off random crap(shimmering water, trees, boats, and other stuff).
You will need:
- Adobe Photoshop (CS to CS5).
- Geographic Imager (free trial available on site).
- A machine with lots of ram (8GB minimum on some datasets).
- Global Mapper (trial available, but doesn't export). I use this to translate the data from one format to another for clients.
- Lots of HDD space.
So you got your color info in, and you have your height data. My first order of business is to make sure that the height data is cleaned. So start by importing your height data into Photoshop. Then bring in the color info and plop it on top of the height data. I make sure to work in 16bit color mode. So from here you use the color info (that is aligned) to check your work as you paint out all the man made things.
It's a loooooong riverway. If you do not need to go underwater, then don't worry about it,just make sure it's consistent. As for the edges, try and match then if you are aligning images. If you are having trouble with the banks, take a look at the trees and how they grow. They give hints on areas where you can't see.
I sample the greyscale data A LOT, and then paint. Painting out a clump of trees for instance, I sample a few points around the clump and paint it out, so the height data won't be perfectly flat. For roadways and such, I don't sample as much to keep it straight. Same for parking lots. Riverways, I sample the deepest point for a section and work my way up. For golf courses, I sample kinda deep, then make all waterways the same depth (this is for the water plane in game engines). Houses, I use the same technique for trees, but I sample OUTSIDE the house lot area. My goal is to try and paint things out to a point before people made stuff on it (minus man-made waterways). So you do this ALL over the image. For each type I am masking out, I add a layer, for instance: waterways, houses, concrete, buildings and so on. From there you load into your 3D app of choice and check the data.
I would imagine for racing sims, the initial tarmac data is removed, then you go in with separate data of the grading, pitch and bank from the track itself and put that geometry on top of the terrain height data. So you'd want to make sure the elevations under/around the track are good.
You are looking for spikes from missed pixels and such. This is VERY important for golf sims. Actually, when it's for a golf sim, or golf course pre-vis you have to look at contour data as well.
The grey looks the same, but it's not, there is a slight grade from south to north. Also sometimes the natural environment will dictate how you tackle things, I can't teach that, it all comes from experience.
Now for the color map. There's many different ways to do it. Depending on what is asked I may clean up the image or I may not. And if they ask to have the image cleaned below are the techniques I use and what types they belong to.
Complete clean All man-made and ground foliage minus grass is removed. Also, you have to look for all the stitching from the imagery. This is used for golf games, videos and ground based sims. I sample larger areas and use a lot of cloning brush. Then I make masks of the area types to reduce the "Hey you used the clone brush" look by bringing in low and high frequency texture data. I bring back all the data and export what they asked for.
Partial Clean I remove man-made stuff of a certain height. This is used for flight sims.
Shadow clean Annoying, but I go in and remove all the shadows from almost everything.
No clean Just for map data usually.
So as you work, save and save often. I also save in *.PSB format when working in Photoshop. Hopefully this will get you looking into other avenues for work in these difficult times. As no one likes cleaning this kind of data!! Whatever you do, don't rush it, as these companies will keep coming back if you put out solid data with a good turn around.
Another thing to look into is the next round of GPS software will be making use of 3D objects to represent real-world locations. Companies are looking for artist.
Hugs and Kisses,
Lamont
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