In this video, Jim describes the difference between raster and vector PDF files and discusses the effect that this can have when working with construction drawing PDF files in Bluebeam Revu. He also describes the effect of not having real text contained in the PDF file.
- Hi, Jim Rogers here, bringing you another episode of Bluebeam Tips and Tricks. You know, I have another weekly series here in the LinkedIn Learning Library called Construction Industry Weekly, and when I started out that series, I talked about going digital, getting rid of the paper drawings, and Bluebeam is a perfect example of one way to do that. In one of the episodes there, I talked about making sure that when you ask for digital drawings, you're asking for a vector PDF, and so, while we're here in Bluebeam, I want to talk about the differences between a vector PDF and a raster PDF, and a PDF with and without real text figures in it.
And, I want to talk about the effect that that can have on the effectiveness of some of the tools that you'll use in Bluebeam. Let's take a look. So, first thing, the major issue with digital drawings and digital PDF drawings is that, to be really effective, you need to ask for a vector PDF. Sometimes, you won't get that. Sometimes, you'll get what's called a raster PDF, and I want to show you what the difference is.
So, quite simply, a raster PDF is just a big image that's on the page. A raster PDF is created by using pixels spread across the page, and each one of those pixels ends up representing lines and figures and letters. But, they're not really lines and symbols and letters. They're just a bunch of dots, they're just a bunch of pixels, and if we zoom in here on this particular drawing that I've got pulled up, you'll see that, as I'm zooming in, things become pixelated, and, you see here, the lines are not sharp at all when you zoom way in.
That's because this is a raster PDF, and these aren't lines on a page, these are dots on a page, and when you group them together, they visually become a line to us, but digitally, they don't represent a line to the software. Now, there's several reasons why that's a bad thing when you're dealing with digital drawings, and particularly when you're working here in Bluebeam Review. One of the reasons is just the time that it takes to render.
So, if you notice, here, that when I zoom out, or zoom back in, it's not instant. It takes a little while for the software to catch up, and redraw that pixel based, raster based image, and, ideally, I would like that to be much faster, so I'm gonna jump over here, just briefly, to an image that is vector based, and you'll notice that when I zoom in and out, it's much quicker.
Okay, let's go back to our raster image for a second. And, you'll see, again, just clicking on that, it takes just a second or two to render that image, as I go to different views. And here, sometimes it hangs up, takes a little longer. The other issue is that this is a much bigger file size than my vector based PDF files will be, much, much larger. So, and then, the final issue is that, when I'm using Bluebeam Review, and some of the measurement tools, to do quantity takeoffs, if I have a vector-based image, and the software recognizes this as a line, or as a wall to this room, I can actually snap to those edges, and if I have a raster based image, it just knows there's a bunch of pixels here, and I can't actually snap to corners.
It's a little harder to be accurate when I'm measuring or filling things in. So, why do you get these raster-based PDFs? Well, sometimes, it's because the image get converted correctly, but most of the time, it's because somebody printed this digital drawing out onto the paper, and then scanned it back in as a PDF, and that's how the PDF was created. Creates a big file, it make things so they're not searchable, it makes it so that you can't snap to lines and walls, and it's not the most efficient file type to be used when you're dealing with these large format, very large sets of construction drawings.
So, let's jump over here to our vector based PDF. You see, again, that's a pretty quick render. As I zoom out, it renders very quickly, and when I zoom in, you'll notice, everything is nice and sharp. Nothing pixelates. I have nice, rounded edges. My dots are dots, they're not pixels. So, lines are lines. That's one element, it's not just something that's made up of a bunch of pixels.
So, that's what I want to have, is a vector based PDF. It makes searching using Bluebeam's visual search tool much quicker and much more accurate, and the file sizes are much smaller. The drawings render much faster. It's just a much more efficient file type to be used in Bluebeam. Now, let's take a look at text, because that is a third issue that we run into when we're dealing with PDFs. So, back over to my raster based drawing.
Again, these aren't lines, they're pixels, and this isn't text. You can see, they are pixels, as well. So, if I do a text search, or I try and select any of this text, it's not gonna let me, because this isn't text. It's just a bunch of pixels on the page. Now, here, I'm a step better, because I do have a vector-based PDF, but this isn't text, either. So, let's zoom in, and I'll show you what I mean. If I zoom way in, you'll see that this text, or what appears to be text, isn't what I'm gonna call real text.
It's still made up of lines and line segments and curves, but it's not text in the sense that it wasn't created using what are called true type fonts. It's text that's made using lines and segments, typically from a CAD program like AutoCAD. And, this is really common, even in a good vector based PDF, to have text that's not really text, because, again, many of the fonts in many of the CAD programs are not true type fonts, so they don't get converted to PDF text.
Now, what that does to us here in Bluebeam is, it means that this text isn't searchable, because again, it's not text. It's just lines and shapes on a page. So, if I want to know whether or not this is real text or whether it's text that was generated from a CAD program, again, I can zoom in like I just showed you, or I can go down here to the text select tool, and I can try and select it. You see, it's not gonna let me select any text, because it doesn't know there's any text there, versus, if I jump over here to my next file, this is a document that I created in Microsoft Word, and then converted to PDF, and when you do that, the text almost always ends up as real text.
And you'll see, if I zoom in here, I don't see any of that lumpiness that I saw on the last one. The curves are still really smooth, and again, that's because this is real text, and using my text select tool, I can click and highlight that text. It tells me it's text, and that means, if I do a text search here, I'm gonna find things, versus, if I do a text search here or here, I'm not gonna find any text, because there's no real text on the page to find.
So, that's the effect of not getting the perfect file type for your digital drawings. Now that you understand the different types of these PDFs that you might end up receiving, and the effects that they might have on your ability to work with these drawings, you start to understand what it is you really want to ask for from your clients, or from the design team, when you're asking for a copy of the digital drawings. You don't just want a PDF file.
Ideally, you want a vector PDF, like this one, that was generated directly from the CAD program where the drawing was created, and, ideally, you want them to have used true type fonts in their CAD drawings, because when they do that, and their CAD drawing gets converted over here to a PDF, those texts will become readable in the PDF version. It'll be real text. Now, what happens when you don't get that? Well, if you have one of these raster based PDF files, and the drawing was obviously created in a CAD program originally, like this one, instead of being drawn by hand, then you might have a copy, like I said earlier, that was printed out, and then scanned in as a PDF, and that's how this one was created.
So, ask for another copy that's generated directly from the CAD file. And if the text in the document isn't real text, and you have Bluebeam Review Extreme, you can run character recognition to solve that text problem. But, I'm gonna say that's a topic for future tips and tricks, so stay tuned.