Computer Aided Design

This weeks assignment:

  • compress your images and videos
  • post a description with your design files on your class page
  • model (raster, vector, 2D, 3D, render, animate, simulate, ...) a possible


    • Compressing images and videos

    compressing images

    Due to our upload limit on storage space for this website, we are forced to compress the typically high-resolution images we take before using them here. For images, in my case, I use Microsoft PowerToys, .
    After installation, it is extremely easy to use. All you have to do is go to the folder where the image or images you want to compress are stored, select one or more images and then right-click and select "Resize with Image Resizer". This opens the Image Resizer menu, which is included in Microsoft PowerToys, among other things. Here we can select how high the resolution of the image should be in the end and have other options to choose from. I am personally a fan of activating the "Overwrite files" option to avoid renaming later. With "Resize" we can compress with the selected parameters and confirm; after that our images should be smaller at best. We can check this by right-clicking on them and displaying the "Properties". There you will find the item size.

    compressing videos

    Unfortunately, you need a different tool to compress videos. Based on Neil's recommendation last week, I use the software for this, which I have also found to be very user-friendly in practice. After installing and opening the program, the dialog below appears, in which I have inserted a video of myself from this week using drag and drop.

    Because I had to upload it on Saturday as part of an aptitude test for the next football coaching license and had to compress it anyway, I used this video as an example for the HandBrake documentation. There has to be something good about spending your Friday evening on freezing artificial turf at -4 degrees.
    As you can see, the video even opens in the preview and the program gives you a range of possible resolutions. In this case, I reduced the preset from 1080p and 30fps to 720p and 30fps because that was enough quality. The file was originally recorded by the phone in 1080p and had a size of 37.5 MB; after compression, the file is only 20.9 MB. The track or the H.264 (x264) encryption is important when compressing, because other types may not be able to be played on all devices. After selecting a storage path, we can compress the video using the green "Start Encode" button. We are then informed about the process via the lower status bar and can then find the compressed video under the specified storage path.

    Computer Aided Design

    raster based 2D design

    This week, to see and demonstrate the differences, I made similar 2D designs in different programs. The first program I used was , which works on a grid or pixel basis. This means that the program creates a grid, just like the individual pixels in the screen you are reading this on. Your screen sets a color value for each pixel. I will try to show what this means here with images of different resolutions. You see a side by side, at the top with a resolution of 720 by 480 pixels (length by height), at the bottom with 20 by 20 pixels for clarity. At the top you can still recognize the dog very well, at the bottom it would be more difficult to make out who the good boy is.


    Here you can already see the blurring caused by the resolution in the grid when you zoom in. The same effect occurs when you show medium-resolution photos on very large screens or with 2D software that works with the grid scheme. It is also called aliasing. Nevertheless, this process, as well as the associated file types such as .png, .jpeg, .tiff, .gif, also has advantages, which is why these formats are still widely used. In the context of digital production, they are rarely seen outside of 2D printing technology.
    To create a simple example, I used the sketch of my final project from last week again. After installing and starting the program, a new file with a neutral background appears. In this file, you can then draw anything your heart desires using the various tools at the top or the different pens and brushes. In my case, unfortunately, this had to be done with the mouse because I don't have a tablet. In combination with my previously very hidden talent for drawing, this is the result.

    To show the aliasing again, I have greatly enlarged the bottom right corner and shown it below.

    Here, too, we see what we saw above. The resolution deteriorates. We can also see that with this form of free drawing, it is not guaranteed that the lines really touch. In a production machine that is supposed to follow the lines as an outer contour in order to cut or mill, for example, these lines would not be usable in this form because the connection is not guaranteed and we will very likely come across open geometries, as with the circles in the image above.

    vector based 2D design

    The problems shown above are solved by vectorizing images. Vector graphics are defined mathematically with real coordinates. Objects such as the following sketch are described by lines, circles and other shapes that have or connect real coordinates. This allows you to work as you like when zooming into the objects without losing focus. In the same way, modern machines like mathematical descriptions and coordinates because they allow you to work very precisely and with repeatable accuracy. Typical file formats are .svg and .pdf, along with many others that are less well known. In this case I worked with the program , which is freely available. It's a good and powerful software, but it certainly doesn't hurt to watch a tutorial before you start. I don't have a specific recommendation for this, because I could already do what I needed to with Inkscape. The probably more important question is whether it will still be like this in a few weeks - so maybe a recommendation will follow.
    When Inkscape is installed and you open it, you first have to create a new project. Once you have done that, the program opens as shown below, with fewer circles, i.e. a blank sheet of paper. Creating the circles was my first task, starting with a circle to which I assigned a diameter of 20.265 mm because I wanted 20 mm and didn't look any further. The normal keyboard commands for Windows in my case also work within the program, so I duplicated my circle using copy and paste. As described above, there are various references to mathematics in Inkscape, but for the design in the top bar, the values ​​for x, y, w and h were important to me. X is the X value of the coordinate of the top left corner of the square that was drawn around the selected circle. Similarly, Y is the Y coordinate. W stands for width and H stands for height, which defines the dimensions of the object itself, in this case the circle.

    Then I drew a triangle around the circles with lines. It is important to say or know that in vector-based programs the corners are typically connected, so they often snap automatically when you want to place a line with the cursor near an existing point. This is an important difference to the pixel-based software shown above. To show that the same drawing operations are possible, I have drawn free lines below with the mouse. Here you can see that they do not snap or snap to the corner points.

    Finally, here is another image in which I have zoomed in on the same section of the image to the maximum. In the bottom right you can see that I zoomed in from the original 141% zoom to 25600%. Nevertheless, the resolution is razor sharp and the lines of the triangle are connected. The hand-drawn line is also sharp, but not caught with the corner of the triangle.

    3D design

    Lastly, or in my case the most important thing for later production, is the 3D design. I used Fusion360 for this because I am already familiar with it. In general, we create so-called sketches in 3D design, just like in vector design. From these sketches, we use various operations to generate 3D bodies to which we can also assign surface properties, as shown in the images, so that we can get an impression of what what we are designing will actually look like in the end. I also recommend looking at tutorials for Fusion360. . 3D design is quite complex and very diverse, so I would recommend trying out what you see in practice straight away, because the overall scope would definitely be overwhelming.
    Here I will briefly describe a few steps on the way to the 3D design of my final project. The design process is very quick but can be seen in full in the video for week 2 on my .
    As you can see on the left, I made two sketches for the entire project. One of them is just for the cups because I needed a different layer reference here.

    Here are my two sketches. With the help of the first one, I extruded a base plate based on the outer line. I generated the side panels from the space between the outer line and the inner line drawn with an offset. I won't be able to manufacture these in this form; I still have to put some thought into this when building the project. The upper plate is also generated from the total area, the circles are cut out from the inside using the second circular line. If we look at the different circles, the outermost circle is the outer diameter of a cup at the top edge. The cups get narrower towards the bottom, where they have the diameter of the smallest circle. Because the base on which the cups stand must later be translucent, I added another circle here, which starts with an offset of 5 mm from the small circle. This would allow light to get past even black cups. Because the cups are next to each other at the top, I need this information in the sketch in order to be able to show how the cups will later stand, starting from the center.

    As already described, I created the cups from the second sketch. I could have done it differently, but it was important to me that they had a realistic edge and the rounding seemed the most logical way to do it. In addition to the pull/push option, which is probably the most common option in 3D modeling, you can also rotate sketches into a body. In this case, I rotated the sketch around the dashed line in 3D to form a body. This option can be found under Solid > Create > Revolve.

    After I had created the first cup, I duplicated it and placed the cups in the correct positions. Finally, I created a ball with a diameter of 40 mm using the operation Solid > Create > Sphere. This symbolizes the table tennis ball needed for the game. Simple shapes can be created this way without a sketch. In addition to spheres, these include boxes, cylinders and pipes. This finally brought me to the following point.

    Then it was time to render the project. Here again, I had no previous experience. For all German-speaking readers, I recommend the following tutorial, which I found very helpful. What I can say is that no one who has mastered 3D design fails at rendering. Rendering is very rewarding and at the same time very cool.
    During the rendering process, I also created a table top in CAD, as in the tutorial. To get into render mode, you switch the area or the drop-down menu in the top left from "Design" to "Render" and have fun with different sceneries. I also tested several backgrounds, but didn't really like any of them, so this week's hero shot is against a flat gray background, but nicely rendered. In that sense, that's it. For the spectacular animation and the design process in the video, please refer to the subpage of my . All further developments will also be found there.


    Download this weeks files