ROAST

The Gradgrind palette editor for RISC OS has been updated, with a minor bug fix for hex display of colour values.

Download link: Gradgrind 0.91 beta (326k)

We’ve had solar panels for nearly 14 years now, and the output has been reported daily on our site. The page is currently generated by a Python program running on a Raspberry Pi (a Pi400 at the moment), but I’ve been working on a version running under RISC OS, using BBC BASIC. Here are some samples of the output:

It’s unfinished as yet, but work continues slowly…

Introduction

As the Met Office is discontinuing their DataPoint service in late 2025, we’ve recently been converting our weather forecasts page to use DataHub, the replacement service. This provides forecasts in GeoJSON format, and gives much more information and better global coverage than DataPoint did. Here we’ll describe how to access the forecasts from a Raspberry Pi, using Python.

Registering

Like DataPoint, DataHub is mostly free for non-commercial and non-bulk usage. Various types of data are available, and we’re using the global spot 3-hour site-specific forecast. This is free providing you access it fewer than 360 times per day.
DataHub requires you to register, whereupon you’ll be given an api-key. This is a string of characters, and is very long! Over 1600 characters, in our case. Store this somewhere secure and safe.

Getting some data

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Gradgrind is a palette generator which takes particular care to create smooth blends between colours. The palettes are generated by curve-fitting rather than linear interpolation (using Catmull-Rom splines, if you’re interested), and can be created and saved as script files as well as edited interactively.

It can create greyscale palettes, which can be particularly useful when loaded into PhotoDesk and used as displacement maps or effect gradients. PhotoDesk can only generate linear blends, which can give visible artefacts, discontinuities and banding.

The program comes with full documentation and example gradient scripts.

Gradgrind is a RISC OS program. It will not run under any other OS.

This is a beta version, 0.90. It was written and developed under RISC OS 5.31. Prior versions of the OS may work; feedback is appreciated.

Download link: Gradgrind 0.90 beta (325k)

Well, first post….