Displays and Input Devices

It's Time for a CAD Monitor Makeover

13 May, 2015 By: Alex Herrera

Herrera on Hardware: Are your desktop displays doing all they can to maximize your productivity?


IPS Technology Improves Collaboration

Do you find that you've often got peers, clients, project managers, or other  collaborators in the next chair — or looking over your shoulder? Then you'll want to consider spending the extra dollars to get a display based on in-plane switched (IPS) technology. IPS displays accurate color from a wider viewing angle (typically 178 degrees) than conventional twisted-nematic (TN) LCD technology, which suffers from annoying color shifts at wider angles. IPS technology has historically cost significantly more than standard TN, but prices have dropped dramatically and are now low enough to fit even the tightest budgets. In fact, IPS is now so economical that it should be considered a default choice for most CAD applications.

Bright Should Be Bright, Dark Should Be Dark

Our eyes care a lot about pixel density, but they care just as much about contrast and brightness. Dialing up brightness raises all pixel luminance, while increasing contrast "stretches" the intensity range to create bigger gaps between intensity values, thereby allowing the eye to better pick up the subtler details. A monitor's brightness is typically measured in candelas per square meter (or cd/m²), with 300 cd/m² a commonly supported peak level that will satisfy the vast majority of CAD users.

Choosing a monitor with adequate contrast isn't nearly as straightforward, however. Contrast is measured as a ratio, like 1,000:1, which means the brightest pixel will be 1,000 times brighter than the darkest. Unfortunately, vendors' measurement methods can vary, and worse, vendors tend to confuse matters by quoting a static figure and dynamic figure, with the latter ratio typically being much higher than the former. In some cases, the static number is left out altogether — even more regrettable for would-be CAD buyers, given that dynamic contrast is going to be far less relevant with consistently lit CAD scenes than, for example, a movie scene that is dark one second and bright the next.

For most common CAD content, simplify your decision by focusing on static contrast (if available), and look for a ratio of around 1,000:1.

Matching Up Interfaces, Cables, and Adaptors

A display makeover should be all about improving productivity — but nothing kills productivity more than wasting half a day at a big-box store looking for the cables or adaptors you need to connect your new displays to your old machine (or vice versa). If you're buying new, you'll want to consider a display that natively supports DisplayPort (DP) connection technology. With DisplayPort, the industry — including both systems and monitor vendors — appears to finally have agreed on a unified, high-performance digital interface.

Converting from one digital standard to another isn't necessarily difficult; adapters are cheap and plentiful. You can convert from DP to HDMI and DVI, and vice versa, but it's always nice to be able to forgo the adapters. However, don't expect to find cheap adapters to go between analog (e.g., the legacy "VGA" 15-pin D-sub connector) and digital. Unless your workstation is getting particularly long in the tooth, you'll most likely be fine with monitors supporting DP and HDMI. But ideally, if you have DisplayPort as well as HDMI and DVI, you should be prepared for just about any scenario, both today and the foreseeable future — no adapters necessary.

Faster Than the Speed of Sight

Getting "caught up" on technology doesn't always require improving on what we already have, because sometimes the performance or capability we had is good enough, and getting more won't make things any better. For example, you very well may not need a faster response time and refresh rate out of your display, if it's already too fast for your eyes to discern.

LCD response time equates to the time required for the liquid crystals to re-align themselves each frame, so the quicker the response time, the higher the refresh rate (Hz) the display can support. There's no need to settle for a monitor much slower than 5 or 7 ms, as capable displays are both economical and plentiful.

But for most eyes, there's also not a compelling need to get a response time that's faster than that. The visual systems of most viewers can't keep up with a refresh rate higher than around 150 Hz, which corresponds to 6.7 ms per frame. So for most people, it's not worth spending extra dollars to pursue a response time beyond the 5–7 ms range.

Supporting Human Multitasking

With all the talk about multicore CPU and GPU technology and the multithreaded software that can leverage multiple cores to multitask, it's worth stepping back and considering what the most effective multitasking component is in today's CAD workflow: it's the user. We humans have a tremendous capacity to initiate, manage, analyze, and monitor multiple tasks in parallel, provided we have the supporting tools to do so. And when running CAD applications and workloads, there is no better tool than a big, clear, precise, and high-resolution display space.

Updating your display setup won't decrease compute times or render scenes faster, but it can make your visual workspace bigger, clearer, and more precise — which can translate to greater productivity than any new high-powered CPU, GPU, or SSD could ever manage.


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About the Author: Alex Herrera

Alex Herrera

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Re: It's Time for a CAD Monitor Makeover
by: rmstangelo
May 14, 2015 - 8:48pm
Excellent article, particularly about the practical contrast ratios, resolutions and response times. Thank you, Richard St. Angelo, Architect
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