science

HHCode

HHCode is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand HHCode rather than just read about it. In short: A Helical Hyperspatial Code, also known as an HHCode, is a data storage format for very large spatio-temporal datasets. The development of HHCode can be traced to efforts in the 1990's by Edric Keighan, Panagiotis A.

Key takeaways

HHCode belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect HHCode to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of HHCode from memory before moving on to harder problems.

Reference excerpt

A Helical Hyperspatial Code, also known as an HHCode, is a data storage format for very large spatio-temporal datasets. The development of HHCode can be traced to efforts in the 1990's by Edric Keighan, Panagiotis A. Vretanos, Michael Galluchon, and Herman P. Varma while working for the Canadian Hydrographic Service's Atlantic regional offices at the Bedford Institute of Oceanography in Dartmouth, Nova Scotia. CHS was facing a problem with storing very large spatial datasets acquired during hydrographic surveys (thus having a temporal element) and was seeking a method to store the datasets in a relational database structure. CHS scientists reportedly conceptualized a spatio-temporal indexing system during a hydrographic survey onboard CCGS Hudson on Georges Bank during the summer of 1989. The indexing system involved an adaptation of a Riemannian hypercube data structure, invoking a helical spiral through 3-dimensional space, which allowed for n-size of features. The actual implementation of the proposed indexing system was termed a helical hyperspatial code and it was first used by modifying an installation of the Oracle database version 4. The HHCode indexing system permitted a highly efficient compression of not only spatial data but other data types as well, while improving search and retrieval times. The HHCode comprises a form of space filling curve and the concept was published by the CHS scientists in the International Hydrographic Review. Oracle Corporation subsequently learned of the innovation which led to an agreement with the Government of Canada which saw the CHS scientists working with a team of Oracle programmers at an office in Hull, Quebec during the early 1990s to redevelop the Oracle database kernel. The resulting software was the Oracle database version 7, with the Spatial Data Option (SDO). Subsequent development of the SDO has resulted in the Oracle Spatial extension to current Oracle databases. With the HHCode being an open-source data format, several spatial data and software companies have adopted it in various products targeted at very large corporate data users, namely Helical Systems Inc. and CubeWerx.

References

Varma, H. et al. A Data Structure for Spatio-Temporal Databases (1990). International Hydrographic Review, Monaco, LXVII(1), January.

Worked examples

Example 1 — a first encounter with HHCode

Start with the simplest possible case. Write down what HHCode claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to HHCode before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about HHCode ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of HHCode

In research: HHCode appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses HHCode in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: HHCode is common in secondary-school and first-year university syllabi. It links to neighbouring topics GIS file formats, Science and technology in Canada, so understanding it makes those chapters shorter.
In everyday life: Look for HHCode outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study HHCode in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what HHCode means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain HHCode out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is HHCode in simple terms?

Why does HHCode matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study HHCode?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on HHCode.