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This page requires a reasonably modern HTML5 browser with
both Javascript and WebGL enabled.

If this message is not soon replaced by an interactive 3D model,
then it is likely that your browser does not support this web app.
Check your JavaScript Console for specific error messages.





Sky Subdivision Type

Sky Subdivision Angle

Available angles will change depending on the sky subdivision type.

CIE Standard General Sky

Sky luminances can vary enormously so this scale will unlock whenever you select a different sky.


Displayed Units

This affects only the display of dimensions within the user interface not their stored value.

Displays editable dimension lines along the edges of blocks when they are selected.


Projection (Shortcut keys: 1 to 6)




Path Lines


Sky Subdivision Type

Sky Subdivision Angle

CIE Standard General Sky

Sky luminances can vary enormously so this scale will unlock whenever you select a different sky.



Time Zone



The aim of this app was to investigate the possibility of generating real-time interactive shading masks. A shading mask is simply a map of which parts of the sky dome are visible from a particular point and which are obstructed by opaque objects in and around a site.

The other key aim was to see if I could implement dynamic sky luminance mapping for use with the shading. The degree of shading at any point is usually quantified by the percentage of the sky that is occluded. However, the luminous distribution over the sky dome is typically quite uneven and varies significantly over short time periods. With this app, you can experiment with a range of different sky conditions and quantify shading based on the percentage of actual sky luminance that is occluded.

Why a Simple Block Model

Actually you can import any type of 3D model as an OBJ file. The app only starts out with simple rectilinear blocks as a way of illustrating the process and providing an interactive site that you can play around with. To load a 3D model, use either the button that looks like a building () or drag/drop the OBJ file anywhere in the app window.

Dynamic Updating

The app automatically detects when a calculation is taking too long to be interactive and will try to degrade appropriately. For example, if the detailed shading takes longer than 200ms to complete, it will try to use a simpler method to maintain the dynamic feedback. If the simpler method takes longer than 200ms, it will stop trying to dynamically update until you finish dragging and release the pointer. Sometimes the browser or system might be busy with something else when you drag, causing it to temporarily stop dynamic updates even on a relatively simple model. However, as soon as the calculations return back to speed, the dynamic update will resume automatically.

Interesting Features

The following are some of this app's interesting features:

  • Using simple axially-aligned blocks to optimise ray-tracing for close to real-time shading calculations,
  • Dynamically updating both a WebGL shading mask within the 3D context of the model and a 2D SVG shading mask to show real-time shading effects,
  • Overlaying sky luminance distributions of the CIE Standard General Sky types that update dynamically whenever the date, time or location changes,
  • Being able to select different sky subdivision methods and subdivision angles to directly compare how accurate the sky segmentation really needs to be, and
  • The ability to display shading in a colour that reflectes the obstructing object.

© Dr. Andrew J. Marsh, 2016.

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.

Drag with the left/right button or a single finger,
or use the arrow keys.
Drag with the middle button or two/three fingers,
or use the A and D keys.
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.


This page uses the following frameworks/components:

Bootstrap  v3.3.2
Copyright © 2011-2015 Twitter, Inc. - github.com/twbs,
http://getbootstrap.com/   (LICENSE)

Bootstrap-popover-x  v1.4.0
Copyright © 2014, Kartik Visweswaran, Krajee.com,
https://github.com/kartik-v/bootstrap-popover-x   (LICENSE)

Copyright © 2010-2015, Michael Bostock
http://d3js.org   (LICENSE)

Google Maps API  v3
Copyright © 2015 Google Inc. - http://google.com,
https://developers.google.com/maps/   (Terms of Service)

jQuery  v1.11.2
Copyright © jQuery Foundation and other contributors,
https://jquery.com/   (LICENSE)

JSON Editor
Copyright © 2015 Jos de Jong - github.com/josdejong
https://github.com/josdejong/jsoneditor/   (LICENSE)

Copyright © 2011 Bruno Jouhier - github.com/Sage
https://github.com/Sage/jsurl/   (LICENSE)

KnockoutJS  v3.2.0
Copyright © Steven Sanderson and the Knockout.js team,
http://knockoutjs.com/   (LICENSE)

Knockstrap  v1.2.0
Copyright © 2013 Artem Stepanyuk - github.com/faulknercs,
http://faulknercs.github.io/Knockstrap/   (LICENSE)

Copyright © 2011 by Evan Wallace - https://github.com/evanw
https://github.com/evanw/lightgl.js/   (LICENSE)

Copyright © 2014 Federico Zivolo - github.com/FezVrasta
http://fezvrasta.github.io/snackbarjs/   (LICENSE)