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Part 2 2nd Exercise: Now we are going to alter a pre-created image, one I rendered in Bryce using a spherical camera. All necessary files are HERE (980kb). Unzip to the same folder as the previous lesson. Don't worry about duplicates, they're all the same. Pre-Lesson Check: OK, hopefully you've kept the CAR file open from the last page. If not, just open it again. The file is also in the download package above. When Carrara asks for the HDR file, load the panorama-ldr.hdr file. This is just the sample panorama image saved as an HDR file, with no editing. Render the file using the saved settings. We can see that the image we rendered looks OK. There is light coming from the HDR image and it lights the scene relatively well. This may be fine from a basic standpoint, but all we are doing is just keeping the low range light and illuminating with it, kind of like using an ambient light setting. We know from just looking at the panorama.bmp image that there should be more light as we have the sun illuminating the scene and it should be somewhat brighter. The sun itself does not show up as being a light source. Go back to the Assembly room and change the HDR file to panorama-hdr.hdr, and re-render with the new HDR. Now we see more light coming from the HDR settings. The differences are not even subtle. The sun now appears as a point light in the reflection of the sphere, and the sky is bright enough that the white textures are truly appearing white. There is a bit of a burn on the top of the models, but that may just be because I was a bit overzealous with my editing. We'll try not to make that mistake with this lesson. Getting Started: 1) Load the LDR file into HDRShop (panorama.jpg) and take the default Camera Response Curve. We can see the image in its panoramic glory. As good as it is, we will change it. Once again, the response curve isn't a contributing factor for what we are doing so we will just accept the default. 2) Hit the - [minus] key to drop the f-stop parameter down 1. If you look at the bottom right of the screen, the "+0.00 stops" is now showing "-1.00 stops." Understanding at this point is still not necessary. Just know that this reduces the luminence of the current image in HDRShop. 3) Click "File", then "Edit in Image Editor." Wait a few seconds. When HDRShop prompts with a window that says "Hit OK when edit complete," switch over to the image editing program. DO NOT HIT OK! This will return the image from the temp file and your subsequent edits will not come through. Trust me, just leave it alone for now. 4) Take a round brush (size=20, hardness=0, opacity=10, color=Pure White, blend=Dodge) and in one stroke, paint over the entire sky of the image. This will allow you to lighten the entire sky. Now we won't be doing this for every step that we do, just for the first 1 or 2 edits. This will lighten the sky enough to be able to produce the necessary effect. This was my error with the HDR file you used above. I lightened the sky too much. Remember, do this in one stroke. If you do it in more, you will have certain areas being lighter than others, and while this isn't a bad thing, it may cause unnatural light areas to appear. 5) Close the image and overwrite the old imagefile. This will save the temporary file back so that HDRShop can refresh the image. 6) Go back to HDR Shop and click the OK button. 7) Hit the - [minus] key again to drop the f-stop parameter down 1. If you look at the bottom right of the screen, the "-1.00 stops" is now showing "-2.00 stops." We're dropping the luminence again. 8) Do steps 4-6 again and check the results. You may notice that the sky is a little brighter but not by much. Putting your mouse over various areas of the sky will yield numbers at or near 1. You don't need to add much more for a decent ambient light, in fact to do so will cause more image burn on the render as the sky is too light. If you really want a test of how the sky looks at normal f-stop, just hit the + (plus) sign to get the f-stop to +0.00. This is the brightness of the normal image. You'll notice that you get a little burning of the sky, but this is normal for a sunny day/evening. Hit the - (minus) key to bring the f-stop back down to -3.00 for the next step. 9) If you didn't check the image, hit the - [minus] key to bring the f-stop down to -3.00. 10) Click "File", then "Edit in Image Editor." 11) Take a round brush (size=10, hardness=0, opacity=10, color=Pure White, blend=Dodge) and paint over the sun in the image. We want to create the light for the sun, so you can go over the sun a couple of times. If you want to create a little more of a corona, just start a little outside the circle for the sun and then in a different stroke paint in the sun. You don't want to do this too many times or you'll end up with an overly bright sun. Remember, SUBTLE. 12) Save the temp file and reset it in HDRShop (like we've done before). 13) Repeat the procedure for a couple more stops, shrinking the brush size and corona (if you've added one). As a faster procedure, just add a small (size 5) point of Pure white (100% Opacity) at the center of the sun at f-stop -6.00. This will give you your point light at a good range, but skips the subtle lighting that you would get in natural light. 14) Click File, then Save as. Choose Radiance Format (*.HDR, *.pic), and then name your file. Then click Save. Rendertime: Now use the Test1.car file to render out the new HDR we've created. When you render you notice that you get a nice even light, but without any major shadows. The lighting scheme we have set up shows this lighting as being at around 256 luminence for the brightest light point, or good ambient light. To create a light that casts shadows make small points (3-5 pixels in width) at 1024. The easiest way to do this is to use a single pixel brush and paint 100% opacity of Pure white into the center of the light source at f-stop -10.00. Don't make this too big as it will really burn out your image. |