This is one of my favourite sections of the PAT (get used to me saying that) because everything you need to answer the question is given to you blatantly . Your only job is to interpret the orthographic projections properly. If you haven’t done so already, I highly recommend reading the PAT Breakdown -keyholes article as it goes into a little more detail about what orthographic projections really are. The following outlines the objective of the orthographic projection/TFE section of the PAT as stated by the CDA:
In this section, you will receive two of top, front, and/or end views of a particular object. The projections are viewed along parallel lines of vision which means there will be no perspective. The picture looking DOWN on the object will be in the top left corner. The picture looking at the END of the object will be in the bottom right corner. And the picture looking at the FRONT of the object will be in the bottom left corner. Note that invisible lines (Lines that are obscured due to a more superficial face) will be represented by a dashed line instead of a solid line. You will be given four answer choices, one of which will complete the orthographic set representing the object.
This is certainly one section that one gets better at with practice. I always tell my students that there are 4 sections on the PAT that one must score 100% on and TFE is one of them. The others are Hole punching, cub counting, and paper folding but we will talk about those in other posts. The following is a general outline of how to tackle this section. Feel free to incorporate your own personal strategies and personalize the list.
- Scan both the two orthographic projections and the answer choices to gain a rough idea of what 3D object you will be mentally working with.
- Find the differentiating factor in similar answer choices and check these differences by analyzing the orthographic projections given.
- Eliminate the answer option that contradict the projections.
- Repeat steps 2 and 3 until correct answer is chosen.
This tactic of comparing and eliminating choices generally works very well. Another tactic involves counting horizontal/vertical lines on the profiles given and comparing with the number of lines on the answer choices. However, this strategy has become outdated as the PAT has adapted to mostly include choices with correct number of lines but with incorrect positioning. For this reason, this strategy will not be discussed. Furthermore, the 3 step guideline outlined above will not only be faster but it will be a more reliable and effective way of choosing the best answer. Here is an example of the DATCrusher strategy in practice:
- Step 1: Scan both the two orthographic projections and the answer choices to gain a rough idea of what 3D object you will be mentally working with. Do not underestimate the importance of this step. With practice you will be able to get a rough idea of the object you will be working with in a matter of seconds. In this particular example, just by looking at the orthographic profiles given and some of the answer choices, I can visualize an object similar to the picture below.
- Step 2: Find the differentiating factor in similar answer choices and check these differences by analyzing the orthographic projections given. This is where the bulk of your time will be spent. It is best to star with an answer choice that you think has potential to be the correct one but this is not necessary for the tactic to work. In this example, options A and B are very similar so we will start there. After a closer inspection, we can see the two options differ in two lines (shown in red). We must now check this difference with the orthographic profiles given as those are the only elements whose accuracy we can be sure of. Looking at the END projection, it’s evident that the lines in question will be visible from top view as there is no face/structure above them.
- Step 3: eliminate the answer options that contradicts the projections. Therefore we can eliminate answer choice B.
- Step 4: repeat steps 2 and 3 until correct answer is chosen. It is important to note that you can take advantage of the initial comparison and further eliminate answer choices with the information you gained. For example, option C has the exact same dashed line that rendered option B wrong. Therefore we can eliminate option C without even performing a projection check! A and D will have to be compared and the FRONT projection tells us that the line in question do not progress to the end of the structure and therefore we can eliminate choice D.
It’s important to note that answer choices do not have to differ in only one aspect for one to effectively compare them. If choices differ in many aspects, simply start at one aspect and progress in the same manner until an answer choice can be eliminated. I hope this article has helped shed some light on the Orthographic Projections/TFE portion of the PAT. Take what you have learned here at DATCrusher, customize it to your liking, and practice it methodically so you can get ready to CRUSH the DAT!