In Cinema 4D R17 the motion tracker has been updated to incorporate a lens distortion workflow. When it comes time to track your footage, the lens distortion present in the footage can introduce significant error into the camera reconstruction. The first step in this process is using the lens distortion tool to generate a lens profile that can be used with the motion tracker, the lens distortion shader and the lens distortion post-effect to remove or add lens distortion as needed. By using a lens profile to remove lens distortion before tracking, you can get significantly better results during camera reconstruction. A lens profile can also be used at render time to distort scene geometries so that it matches the lens distortion in your footage. So, let's take a look at creating a lens profile. To create a lens profile, you're going to use the lens distortion tool. The lens distortion tool can be found in the tools menu under lens distortion. Once the tool is active in the attribute manager, you can click on the open file button to bring up your open file dialog. From here, you're going to want to select an image that has lens distortion present. In an ideal situation, you'll shoot a lens grid using the lens that you shot your footage with. In the case of our video, we used a GoPro 4 Hero and we also shot a lens grid. If you'd like more information about shooting a lens grid, check out the link in the description of this video. With the image loaded in the viewport, we can get started. We're going to go to the lens distortion tab and then choose the solve mode. There are two different methods for the solve mode: automatic and manual. Automatic is a great way to get most of the settings that you need correct and then you can switch to manual to adjust if needed. So, we're really gonna focus on automatic in this case. The first thing that we want to do is add an end point line. This is going to add a line with three points along it. We want to align the points on the line to dots on our grid. We want to pay close attention to the grid and make sure that the line is matching dots that all share the same row. In this case here, we can see that this point should actually some down one. Now, even with this little work done, we can choose a lens distortion model. The lens distortion model should match the type of lens that you were using as close as possible. In the case of the GoPro 4 Hero, we're using something similar to a radial fisheye lens. As soon as we select this lens distortion model you'll see some lens correction being applied to the footage inside the view port. Next, we can click on auto-solve. We'll see that these sliders in the attribute manager adjust to give us the general settings for the lens distortion. If we want a better view of this, we can go to the image tab and then scale the view using the image scale. If we zoom in, we can also hold down control plus shift and left click and drag in the viewport to move the view around so that we can get a closer look at our image. We can see currently that there's still quite a bit of distortion present in this image. The dots along this row should be lining up with our end point line, but they're not. So we're going to start by adjusting the positions of these a little bit more and adding in another reference line. So go back to lens distortion and set the model to none. Then we're going to zoom in a little bit and readjust our points, making sure that the points are lining up with the center of the dot as close as possible. And then click on full image to go back to the full view and we're going to create a duplicate of this line. To do that we'll hold down control and click and drag an existing point on the line. We can then readjust the points so that they line up with the proper row. Again, we can zoom in using the image scale attribute and then pan the view using control shift plus left click and drag. And those look pretty good so we'll go back to the full image. Set the lens distortion back to radial and auto-solve again. Now if we zoom out to check, we can see that things are looking a little bit better but they're still off in the center area here. So let's go ahead and zoom in and we're going to add some more points along the end point line. Set the lens distortion model to none and then we're going to count out a few dots along the row. One, two, three, four, five, six, seven. And then we can control click on the line to add a new point and readjust it's position. We'll do the same thing for the other side. One, two, three, four, five, six, seven control click and then move the point. We wanna do the same thing for the bottom. This time we'll just follow the column down, control click to add the point and reposition it and the same thing for this side. Follow the column down, control click and then move the point. We'll go back to our image tab, full image, lens distortion, radial fisheye and then auto-solve again. Now you can see that the dots on the grid match the end point line a lot better. We can go to the image, scale out a bit and we can see that there's a little bit of distortion there so we'll go to our lens distortion and we'll just roll back our sliders a little bit until we find the ones that are going to give us the best result. If we need to we can always click auto-solve and that's going to reset things back the way they were before we started adjusting these. And so again, we're just looking to make sure that the dots all line up. We can also go to manual mode and click add line. And this is going to give us a simple reference line that we can use while we're adjusting these sliders. So set this back to none and then change the position of this line so that it matches up with the column here. I'll go back to my radial fisheye and you'll see that that loads back in and now as I'm adjusting I have a better frame of reference for trying to line up these specific points vertically. Once I have something that looks more or less correct, I can then save the lens profile. So click on save lens profile and then we're going to give this a name. Preferably it should reference the exact lens that you were using so that you can use this profile later on with any other footage that was shot with that lens. In this case we'll just take the name of our lens grid and we'll use that. Now we're ready to take our lens profile and start using it in the rest of the lens distortion workflow.