For those of you that don’t know, GIMP stands for GNU image manipulation program. It’s free to download and could be compared to Photoshop or an extremely advanced version of paint. For someone interested in showing off his or her project, it can be a very valuable tool. In this post, we’ll be going over the best ways to put dimensions on your drawing. In other words, you’ll be describing in inches/feet/centimeters or whatever units you desire (parsecs?) how big certain elements of an object are.
The simplest way to do this is to first open an existing picture of the object you wish to illustrate using GIMP. Use the pencil and text icon (outlined in pink) to draw the lines and letters with arrows on the ends (like the blue “24” on the right). This works fine, and will work for simple drawings that you are never going to modify. Save it as a new .jpg or .gif and you’re done.
The problem with this method comes when you make a mistake or want to change something later. If everything is on the same layer, it is very hard, if not impossible, to change your dimensions without it looking terrible. The solution is to open your picture as before, then make a new layer for the dimensions. When draw things on a second layer, you can modify the dimensions all you like without disturbing the original picture or drawing.
Layers are a bit difficult to figure out at first in GIMP, but if you open up the layers dialog as shown to the right, things become a bit simpler. This dialog box will display all of the names of your layers as well as a thumbnail of each one. Select which layer to work on by highlighting it and select which layer or layers to see by clicking on the “eye” icon in the dialog. See this video for more info on layers.
In the example to the right, you can see both the “dimensions” layer and “Background” layer. You can select which one is displayed with the “eye” icon. If you were to draw something, it would be saved on the dimension layer because it’s highlighted in blue. In this state, you are able to edit something on the dimensions layer without affecting the background picture. If you need more layers, you can add a new one by simply right-clicking in the dialog and selecting “new layer”.
So as an example of how to use layers to dimension a photo or drawing, here’s a dimensioned photo from an upcoming post about building a cornhole toss set. I drew this with only one layer thinking it was simple enough, however, after proofreading, this board was obviously not 24″ by 24″. Unfortunately, everything was in one layer so I couldn’t change this without erasing some of the photo. I instead redid this in two layers.
I liked the blue color that I had used in the previous drawing so I opened the dimensioned picture along with an unmarked version of the boards. While working with the unmarked version, I added a “dimensions” layer. I then selected the incorrectly marked version and used the “color picker tool” (looks like a medicine dropper) to select the blue color that I had previously used.
Clicking back on the unmarked, two-layer version, select the dimension layer and draw the dimensions with the pencil and text command as you would have before. The difference this time is that you can now select only the dimensions while making changes. So if you put 24″ again, which for some reason I did, you can just erase it and change it to 48″ without affecting the actual board picture.
Also, if you find the light green doesn’t work with small pictures on the internet, you can easily change this with the “bucket fill” command. You could do this without layers, but I also decided to also take out the “grain direction” text. That you couldn’t do. So after all that, this is what I came up with:
To put on this website, I saved this as a .jpg file which will make everything into one layer. To be able to edit your drawing/photo at a later time, save it as a native GIMP draw file which will give you an extension of “.xcf”. This will preserve the layers and allow you to edit as you see fit. Also, experiment with holding the shift key to draw straight lines. That should help as well.