Overview
The aim of this app is to let you read and display EnergyPlus weather data
files. It maps weather data by day of the year in the X-axis and hour of the day in the Y-axis,
showing each of the available weather metrics as a 3D surface varying in the Z-axis.
Weather data can fluctuate wildly from day to day and even hour by hour,
so some form of averaging is usually required in order to better identify trends. I have found
that using a rolling average to smooth out these fluctuations provides a particularly useful
insight for this type of data.
This basically means calculating the hourly data for each day by averaging over
a given number of days both before and after it. Using a 28 day rolling average period for example,
the 1st of January becomes the average of the last 14 days of the previous year and the first 14 days
of the given year. For the 2nd of January, the hourly data from the 18th of December is subtracted
from the running total and that from the 15th of January is added, and so on. As EnergyPlus weather
files provide a representative year for each weather station, the previous year is assumed to be
exactly the same as the given year so the data is simply wrapped.
Background
I needed this app to visually verify that I was reading the EPW file format
correctly and extracting valid data for each weather metric. It also allowed me to have another go at
contour banding as my first attempt in the daylight analysis app wasn't as robust as I really wanted.
However, I'm pretty sure I've cracked it now so I'll go back an update the daylight tool when I can.
Interestingly, when weather data fluctuates wildly and you are using a non-linear
color scale to represent values, a triangulated grid with vertex-based colors does not always give the
most accurate representation. This seems to be an issue that is rarely noticed or addressed, but it
occurs when a triangle has vertices with a very wide variation over the scale range.
OpenGL and WebGL only does a linear interpolation of colours between vertices so
you can sometimes end up with small areas having a hue that doesn't actually occur anywhere within the
color scale being used. I have noticed this in a couple of previous projects and it has bugged me for
a while, so I was really keen to experiment with a more accurate pixel-based color scale in these graphs.
Interesting Features
The most interesting features of this app are probably:
- The speed with which data averaging can be done, meaning that changes to graph parameters
can update the surface grid in real-time on most devices,
- The directness of user interaction when dragging axial sections, my animation libaries
are getting better now so hopefully things 'feel' more responsive and direct,
- Calculating contour lines has always been fine, but now the filled banding is much more
robust and no longer suffers from sporadically infilled island effects,
- Calculating the color scale representing metric values using a fragment shader for
absolute pixel accuracy rather than using color-by-vertex, and
- Some of the transitioning between grid states can be a bit of fun, especially if you
play around with different easing functions and transition speeds.
© Dr. Andrew J. Marsh, 2017.
View Manipulation
You can interactively adjust the 3D view of the model using a mouse,
pen or stylus, or by touch on a tablet or phone.
You can also use the items in the 3D View Settings popup.
- Rotation:
- Drag with the left/right button or a single finger,
or use the arrow keys.
- Panning:
- Drag with the middle button or two/three fingers,
or use the A and D keys.
- Zooming:
- Use the scroll wheel or pinch with two fingers,
or use the W and S keys.
NOTE: You can use the Shift and Ctrl/Meta keys to adjust the increment
of each scroll event or key press.
Keyboard Modifiers
The Shift and Ctrl/Meta keys are used pretty extensively
to modify interactive data entry. This applies to all increment buttons, scroll wheel motion,
slider controls and input elements.
- Shift Key:
- Increases input to larger values, usually by ten times or significantly larger increments
such as 1 month for dates and 1 hour for times.
- Ctrl or Meta Key:
- Decreases input to smaller values, usually by one tenth or the smallest reasonable increment
such as 1 day for dates or 1 minute for times.
NOTE: You can use the scroll wheel to edit a data value when hovering over any slider,
numeric input or even table rows that indicate their editibility.
Loading - please wait...
