Sky Distribution Equations 18 Dec, 2018
A number of people have asked me for more information about a comment I made in the CIE Sky app description about using the "latest" sky distribution equations. Basically, whilst trying to work out why the numbers I was getting from my implementation of the CIE Standard General Sky were slightly different to those from other popular daylight tools, I noticed that all of them appeared to be based on code that implemented the original Perez All-Weather Sky equations published in 1993, rather than the CIE Standard General Sky equations from 2003. The differences between the two are relatively small, but certainly enough to confound any direct numerical comparison.
Earth/Sun Relationship Update 12 Jun, 2014
I've been doing a fair bit of low-level optimisation work on my solar calculations code recently and, whilst I have a reasonably extensive test suite for it, nothing beats being able to actually see things in action and interactively put them through their paces. Also, I've been wanting to update my old Earth/Sun Relationship app for a while now with some new ideas and graphics, so the synthesis seemed pretty logical. Thus, I just finished a brand new version with lots of new features as a way of both examining and visualising the relationships involved and letting me test and validate the core code.
Processing Libraries - Where are They? 26 May, 2014
As I've mentioned in previous posts, I have been working on a graphical user interface and 3D modelling library in Processing for some time now. I originally chose Processing because it was truly cross-platform and the only tool that also supported embedded web applets. I got to a reasonably advanced state in v1.5.1 and then, of course, everything changed. Processing 2 moved entirely to OpenGL and completely abandoned web applets.
Dynamic Charts in WPF 02 Aug, 2013
There are a plethora of WPF charting solutions out there, both commercial and open source. I have tried quite a few but have yet to find one that is capable of handling highly dynamic data whilst also providing useful customisations such as centered axis or generating polar diagrams. I do most of my dynamic charts in OpenGL but labelling axis and data points using textured fonts lacks some of the polish I have seen in many WPF-based solutions. Thus I thought that, for my Windows apps, I would try porting my OpenGL chart library to WPF.
Event Handling in Analysis Classes 22 Mar, 2013
As I have mentioned in a couple of other posts, I have been working on the API for a suite of building performance analysis classes, with a particular focus on dynamic visualisation and interactive manipulation. Part of this involves implementing an event notification system so that changes can propagate through even the most complex object hierarchies without the user having to worry about the internal plumbing. Unfortunately the standard approaches that I have found aren't particularly suitable here, so I have had to hack out something of my own.
Where's the Point in 3D APIs 28 Sep, 2012
Whilst working on an analysis library recently, I have been trying to reconcile how best to define positional and directional information. Most 3D frameworks and Application Programming Interfaces (API) use a single
Vector class (or similar) to define a generic object with X, Y and Z properties, which is then used interchangeably to describe both points in space and direction vectors. The closer I look, however, the more I think that it's important to clearly distinguish between the two and treat them as separate classes in an API in order to avoid inadvertent user mistakes. Unfortunately there is no single knock-out justification for either approach, so the following are some simple contemplations on the subject as I try to work out which way to go.
Designing for Sub-Classing in Java 23 Sep, 2012
One of the projects I have been working on over the last few months is a graphical user-interface (GUI) library for Processing. The Java API to the library makes extensive use of sub-classing and the intention is that it be easily sub-classed by the end user to allow for deep customisation of its functionality. Deep customisation means allowing for any property in any of its classes to be easily overridden. Sounds trivial as this is what object-oriented programming and Java is all about, but it actually leads to an interesting code-design dilemma.
Fast 3D Vector Text in Processing 07 Jan, 2012
Technical illustrations and 3D graphs tend to need lots of different kinds of text - some bold/italic, some large/small, and often in a range of different colors or shades of grey. Having struggled with image-based font glyphs in 3D for ages, I've kinda had enough - so set out to develop my own parametric vector text in Processing/OpenGL. This applet is a demo of some of the types of 3D text object I've been playing with as well as some experiments with annotation arrows.
Dynamically Dimensioning 3D Models 28 Dec, 2011
When interactively manipulating objects in 3D, having clear dimensions that update dynamically while dragging around allows for much greater confidence and accuracy in the process. This is especially true on a tablet where accurate alignment is well near impossible as your finger (and sometimes hand) effectively obscures the drag point. However, what started out as a quick experiment ended up sucking me into a 6 day vortex, swirling around with quaternion maths and 3D text manipulation in an attempt to get radial dimensions visible when viewed from any direction. This tiny applet is the result of those 6 days.
gluUnproject() for P3D and OPENGL Sketches 04 Dec, 2011
I have been struggling for a while in Processing with the reverse projection of 2D screen coordinates back into 3D world coordinates. It's relatively straightforward in OPENGL sketches using the JOGL view matrices and the GLU.gluUnproject() function. However, I could never get anything solid when using the P3D renderer or the PGraphics3D matrices. For some reason there was always a slight scaling issue which varied with different views. Previously I've used fudge factors to get it pretty close but, as I still prefer P3D for browser embedded work, I finally spent some time on it and made the breakthrough I needed. This is a brief description of what I learnt along the way as well as a demo applet and custom gluUnproject() function.
A Small Mac Mini Server Cluster 02 Nov, 2011
I have recently been building a small multi-node cluster of Mac Mini Servers as a development tool to explore some cloud services and parallel processing techniques. For this purpose, the Mac Mini is great as they are dead quiet, use very little power, boot with no problems without a keyboard, mouse or monitor attached and are easily set up to allow full remote management, configuration and screen sharing. For me the Server version is best as only they come with an Intel quad-core i7 CPU, giving effectively 8 processing nodes each. The CPU speed is a bit slower compared to the best non-server version (2.0MHz vs 2.7MHz), however the non-server version is only dual-core.
Analytical Space Inspection 07 Aug, 2011
When dealing with complex analytical models, visually checking that all the spaces within a building have been generated correctly is never easy. This is because there are usually so many of them and their bounding surfaces are invariably adjacent to those of other spaces. You often wish that there was a way to 'explode' the building apart so you could see all of its constituent parts. Well, this the first of my experiments to do exactly that.
Super Shapes Generator 12 Jun, 2011
Having just done the Spherical Harmonics demo, and with most of the infrastructure already in place, it would have been remiss not to do a Super Shapes demo. Super Shapes are 3D forms generated using Johan Gielis' generalisation of the superellipse formula, often termed the superformula. This was proposed in 2003 as a framework for simulating natural forms and is basically an equation with four input parameters that generate a range of natural polygons.
Spherical Harmonics Shape Generator 05 Jun, 2011
I have recently been looking at the use of spherical harmonics as a way of doing real-time diffuse lighting and shadowing effects in OpenGL. As I usually only really understand stuff when I can see it, I did a quick viewer in Processing to help make sure I was getting all the algorithms correct. Some of the visualisations and shapes started to look pretty good, so I figured I’d polish it a bit and put it up on my site.
Surface Shading - Take One 31 May, 2011
The intention of this next iteration on the theme of overshadowing was to look at surface shading on a glazing panel. Unfortunately I got a bit bogged down trying to work out interactive design rules for louvres and brise soleil so didn't get as far as I'd have liked over the long weekend. However, I did finish a basic horizontal/vertical shade example and thought I'd put it up as, even though it doesn't yet show the shading effect on the glazing surface, simply being able to drag a shading mask around seems to give some useful insight into the solar aperture and obstruction effects.
Real-Time Site Analysis - For Android 16 May, 2011
The latest version of Processing makes exporting sketches directly to Android relatively easy. However, as everyone on the Processing for Android wiki keeps saying, interacting with a mobile app is very different from using a standard mouse and keyboard. My aim has always been to develop and maintain a single code base to serve all platforms, for both libraries and sketches. This update is the first of my attempts to get this happening on my Samsung Galaxy Tab, which I use for testing such things.
Real-Time Site Analysis 03 May, 2011
I often find myself trying to explain the concept of shading masks - typically over the phone which is never easy. Thus I thought I'd try both demonstrating and illustrating the basic ideas in an interactive web app. In the end it turned out far better than I ever thought it would as I managed to get the required ray-tracing working in pretty much real-time. The aim is that, as you interactively manipulate the 3D model or drag the position of the dome around, you can see instantly the resulting overshadowing effects at the dome centre, thus better understanding their relationship.
3D on the Web - Back to Processing... 30 Apr, 2011
Finally got some time to play with Processing again. It's been a hugely busy year with work and I have literally had no time to do any of my own stuff - you can see it's more than a year since my last post on this site. But, like many people in the UK, I took vacation time either side of Easter to take advantage of the Royal Wedding and May Day bank holidays. This gave me a bit of breathing space to look at WebGL and basic app development on iPad and Android, something I'd been looking forward to for a while. However, I always keep coming back to Processing.
Real-Time Dynamic Daylighting 11 Apr, 2010
Understanding the potential distribution of daylight in a room is a really key design skill. This applet lets you interactively manipulate windows in a room and see the daylight distribution recalculate and update in real-time. This really highlights the cause-and-effect relationships involved and helps develop that understanding. In addition to just showing daylighting, you can also overlay daylight factor protractors or frequency distribution data and see the effects of different surface reflectances on internally reflected light.
Simple Parametric Modelling Experiment 28 Feb, 2010
This applet is an experiment with parametric modelling. The primary focus was the development of an interactive parameter class with a securely bounded range, variable precision, detailed string formatting, tweening/animation support and direct bindings to both the slider and 3D model classes. The result is a simple parametric tower model. This is relatively simple geometry, but I am really quite surprised how fast Java-based graphics can actually be, and this isn't even using OpenGL.
Cosine Law and Surface Incidence 01 Feb, 2010
Surface incidence is governed by the Lambert cosine law. This states that the relative intensity of radiation or light on a surface is equal to the cosine of the angle of incidence, and that the relative area over which it is distributed is the inverse of this value. This applet provides an interactive and highly visual demonstration of this effect on both horizontal and vertical surfaces. You can interactively drag altitude and azimuth angles to see changes in both the distribution area and relative intensity of an incident energy beam. It is particularly interesting to see these effects simultaneously on both surfaces.
Sun-Path Diagram Projection Methods 17 Jan, 2010
Most of the real detail in a sun-path diagram is usually around the horizon. This is where adjacent buildings, trees and other site objects provide the greatest levels of obstruction. To increase detail at these low altitudes, different sun path projection methods can be used to essentially 'squeeze' altitude angles towards the zenith and expand them around the horizon. This applet demonstrates the most common altitude projection methods and shows how they can be mapped in both sky-dome and orthographic sun-path diagrams.
Horizontal and Vertical Shadow Angles 10 Jan, 2010
Horizontal and Vertical Shadow Angles (HSA & VSA) are very important when dealing with the design of shading devices. As opposed to solar azimuth and altitude angles, shadow angles are always taken relative to a particular surface. This applet presents a visual illustration of the complex relationship between location, solar position, orientation, tilt and shadow angle. Interactively changing the date, time and location is the key to developing a visual understanding of this fundamental shading design concept.
The Earth-Sun Relationship 10 Jan, 2010
This applet demonstrates the geometric relationship between the Earth and the Sun, showing the resulting illumination pattern at any time of the day and year for any location. All factors such as declination and the equation of time are fully considered and accurately modelled. It allows you to overlay information such as annual sun paths, important latitude/longitude lines and world time zones. You can rotate around the Earth in any direction or lock into a geo-stationary or view-from-sun perspective. Both annual and daily solar cycles can also be animated to better appreciate subtle effects.
Solar Position and the Sun-Path 04 Jan, 2010
Sun-Path Diagrams are a way of modelling and visualising the path of the Sun through the sky at a specific geographic location. With a little interactivity and a small element of play, such diagrams can significantly contribute to our understanding of how the Sun is likely to interact with a building - a concept crucial to the effective design of shading systems. This applet presents just such a Sun-Path diagram, allowing you to interactively change date, time and location as well as viewing it in a range of different ways.
Graph - Robustness Calculator 01 Nov, 2009
A significant problem in the performance analysis of buildings is trying to understand hugely complex data sets that often results from the investigative process. These types of analysis are usually focused on the potential effect of different design parameters on the performance criteria we are designing to meet. The type of graph described here provides a simple means of interactively investigating and visualising complex relationships that may exist within a large number of calculation runs.
Graph - Annual Temperatures (Google) 05 Aug, 2009
The graph is one of my experiments with Google's Visualisation API as a possible means of interactive web-based data presentation. It's an implementation of an annotated time line graph that Google originally developed for showing stock exchange data - used here to show annual hourly air temperature values. It has to process a whole year's worth of hourly temperature data for San Francisco, so it can take a little while for the graph to first appear.
Graph - Annual Temperatures (Java) 27 Jul, 2009
This is an experiment with the use of Java applets to provide highly interactive charts and graphs embedded within a web page. It is just an example so the data it shows is not hugely meaningful - in this case a set of annual hourly air temperature values. However, it is an opportunity to play with my primitive attempt at an interactive and intuitive date range control. This control sits at the bottom of the chart and provides a means for selecting a date range for the values shown.