Measure for measure

It seems to be a Dr C day.

In yesterday's "Friday crab blogging (late)" post, the good doctor twice refers to “...the English Pound, that funny letter "L,"...”. Ignoring the usual USAmerican conflation of "English" and "British" (analogous to the calling all USAmericans "New Yorkers" or, I concede, the British habit of calling anyone north of Mexico "Yankee") it's true that symbols are often perplexing.

The periodic table offers every child the puzzle of Ag for silver, K for potassium and Pb for lead. These derive, like "that funny letter L", from Latin origins: argentum, kalium, plumbum, librae, respectively.

Why "librae"? The Roman system of currency, before its departure from Britain, was arranged in a three tier system in which librae (from libra, the Roman standard unit of weight – from which also comes the abbreviation "lb" for the pound weight) were subdivided into solidi and then into denarii. The resulting abbreviations somehow survived Saxon and Norman invasions, to become the "£sd" (Pounds, shillings and pence) system which was still around through my youth and early adulthood.

For those too young to remember, there were twelve pennies, or pence, (d) in a shilling (s) and twenty shillings in a pound (£). In a sudden spasm of common sense (vigorously contested, but successful) when I was in my early twenties, the United Kingdom replaced this lovable but unwieldy cultural heirloom with a shiny new system. There were now one hundred pence (p) to the pound (still £).

The rest of Europe has since leapfrogged on from its various ancestral currencies to an even shiner and newer system: the common currency Euro, represented by a funny E (€) which has the virtue of a direct link to the currency unit. The UK has yet to find much enthusiasm for this obvious next step ... another 1300 years, perhaps.

The rest of Europe, and indeed the rest of the world, also shows greater enthusiasm than the UK for adoption of other standard measures – in particular, adoption of the almost completely logical SI system. The UK has adopted the system, but not to the extent of replacing day to day use of older customary units, which is somewhat confusing. The US (in company with those other two great global leaders Liberia and Myanmar) hasn't adopted it at all, preferring to stick with a quirkily unique variant on the Imperial system used by ... um ... nobody else.

So, to return to the point, the "funny letter L" is an abbreviation inherited from a predecessor currency whose name actually did start with an L.

The US, of course, uses the Dollar, the name of which derived from an old European silver (Ag!) coin called the Taler, and so its symbol is a funny letter T. Oh, wait a minute ... no it's not ... it's a funny letter S ($). Explanations for this vary, with the front runner being ... that ... S is an abbreviation for ... "Spanish peso" ... at this point, since my head hurts, I will hand you back to Dr C... or even onward to JSBlog, which has a stronger stomach for such labyrinthine historical cold trails than I...

Time for a cup of coffee and a shortcake biscuit.

I may not know anything about art, but I know what I like...

A week or so back along, or thereabouts, I posted a response to Dr C's comment on an Unreal nature entry. Then I took it down again, a few hours later, because it was garbage (my post was garbage, that is; not Dr C's comment). Since then, a conversation has ensued through another Unreal nature post and its comments followed by a post from Dr C himself along with its own cargo of comments.

Quite apart from the discussion itself, Ray Girvan's three artists' statements about his own work, "My Crime", are worth a hundred times the entry money on their own.

But ... for me, the content of the discussion is perpendicular to its subject. (And if you can make any sense out of that metaphor, please let me know!)

I've said before, more than once, that I don't think "what is art" debates can go anywhere. I just wrote a sentence about signification domains and platykurtic uncertainty envelopes, but that doesn't go anywhere either so put it aside.

Art is, in words used by Ms Heyward in another time and place, "what you think it is". That's it. That's all there is, except that "you" can take three (possibly more) meanings.

1. You, the creator of the putative piece of art.
2. You, the viewer of the putative piece of art.
3. You, plural, a sufficiently significant number of people (who may not, curiously, in many cases, have either created or viewed the putative piece of art) to constitute an influential consensus.

So long as at least one "you" defines something as "art", then that something is art.

Number 3, the consensus, can be generated in any number of ways ... some spontaneous, some artificial. If the artist passionately believes that her/his work is art, that passion can persuade others. If an influential viewer believes that s/he is seeing art, that too can persuade others. Very occasionally a sufficient number of viewers share the same response and generate their own consensus.

Dr C suggests that there might not be a clear divide between "art" and "not art". I agree; I'm inclined to the view that the two poles are of dubious reality while the fuzzy space between them is manifest.

Ray suggests that if he displayed his "my crime" collection of ketchup bottles he would be thought deluded, or a charlatan. This belief on his part probably makes that outcome very likely, while belief in the display as art might have a chance of producing viewer consensus (as, of course, might a sufficiently convincing hypocritical pretence at belief).

I never really think about whether or not what I do is art; I just do it, because I want to or because (in an inner sense) I must. If asked, I would probably dither and, eventually, say "I don't know" (or just wander off with a headache). But Dr C is kind enough to describe some of it as art; and, by that moment of being described so, it definitively becomes art.

Being art doesn't necessarily imply any particular meaning or value for "you". I would define Damien Hearst's bisected quadrupeds as art. I see intellectual and philosophical interest in them. They do f*** all for me personally, and I would rather have a nice bit of driftwood ... but they are still art, because I think they are. (So, of course, does the capital art market, which gives them separate consensual existence as art).

Dr C describes himself as "a label sort of guy". Most of us, I think, are – it's the price we pay for the manifold benefits of the Enlightenment. But labels are not what they describe: and vice versa. The more precisely we define the label, the more we lose our grip on that which it describes. A completely and precisely defined label would describe nothing at all: that's the nature of natural language. So it is with art.

Art is art because somebody believes it to be. Beyond that lie arguments about precisely how many angels can dance upon a pin.

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Previous related rants:

• Dreams, talents, soldiers...
• Labels, and other romances
• What's in a name?

Accuracy vs precision

I'm getting a modest but insistent shoal of queries about the distinction between "accuracy" and "precision" in the Collisions post. Several correspondents offer entries from dictionaries to support the contention that these words are interchangeable.

I also note the comment to that post that I ask too many questions. So, no questions this time: just explanation.

For a statistician, and for any scientist who takes a statistical view of data (which is to say, almost all present day scientists) the distinction is between central tendency and dispersion respectively. If you've not had contact with those terms, that won't have helped – so here's a visual illustration which I use for teaching. Imagine that four people each take turns firing six rifle shots at a target. All of them are aiming to place every shot at the dead centre of the target. When they've all finished, we compare their results and find the following (double click on any target for a larger view)...

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Avril's shots are all placed right inside the central circle, very close to the true centre. We say that her shooting is very accurate.

Her shots are also clustered very close together, in a small bunch. We say that her shooting is also very precise.

Avril's shooting is both accurate and precise.

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Brian's shots are also clustered close together. We say that his shooting is just as precise as Avril's.

However, this cluster is a long way off the centre of the target at which he was aiming – so we say that his shooting is much less accurate than Avril's.

Brian's shooting is precise but not accurate.

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Carole hasn't managed to group the shots very closely together; they are scattered over a much wider area than either Avril's or Brian's. We say that her shooting is not precise.

On the other hand, the centre of her cluster is pretty much on the centre of the target – so, despite their spread, the accuracy is as good as Avril's.

Carole's shooting is accurate but not precise.

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Finally ... Dave's shots are even more scattered (less precisely grouped) than Carole's.

And their centre is some way to the right of the target centre – so less accurate than Avril's or Carole's.

Dave's shooting is neither accurate nor precise.

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Clear as mud? Good, good, good. I'm off to mow the carrots.

A replacement for camera lens focal lengths

I long ago lost patience with the continual mental conversions between 35mm and digital lens focal lengths.

At the same time, I also don't like the habit of giving a false focal length in order to convey an angle of view (AoV) or magnification in 35mm terms: focal length affects other crucial things (depth of field and focus, for example) as well. Far better to disconnect the focal length figure from the imagined magnification and AoV in favour of a measure that worrks on any format.

For that reason, I started use a system of ratios in percentage form. SO, for example, a standard lens is around 100%, a wide angle is less than 100 percent, a telephoto is more than 100%. Since people keep asking me for paper copies of it, only to get the grumpy answer that it has to be in their head own, here it is for anyone interested. Print it if you wish, or modify to suit your own needs and internalise it as I have done ... or add a small sticker to every lens, marked with its ratio for quick reference.

For convenience, the ratios are in colour coded blocks - very wide angle, moderately wide angle, roughly standard, moderately telephoto and very telephoto. Please don't write and tell me that you would have grouped them differently; it's all subjective, and we all have our own ideas ... if the colours are not helpful, ignore them or change them to suit you.

All ratios are calculated on the basis of the theoretical (not conventional) standard lens for the format concerned. This is a value equal to the diagonal measurement of the negative, slide or digital sensor in use. The exception is 35mm, where I have added a second set of bracketed figures in italics: The main figure relates to the theoretical standard lens of 43mm, the italicised and bracketed one to the conventional 50mm lens.

I can't include every possible focal length, nor every DSLR sensor size. If you want to generate your own table, with more useful examples for your purposes, but are not sure of the process, email me (address in the header of this blog) and I will send you an Excel spreadsheet to do the work for you.

Crude focal length comparisons
Actual focal length	DSLR ratio (APS/C 1.5)	35mm FF film ratio		6x6cm film ratio	6x7cm film ratio	5x4inch film ratio
10	36%	23%	(20%)
12	43%	28%	(24%)
14	50%	32%	(28%)
15	54%	35%	(35%)	18%	16%
17	61%	39%	(34%)	20%	18%
18	64%	42%	(36)	21%	20%
21	75%	48%	(42)	25%	23%	13%
24	86%	55%	(48)	28%	26%	15%
28	100%	65%	(56)	33%	30%	17%
30	107%	69%	(60)	35%	33%	18%
35	125%	81%	(70)	41%	38%	21%
40	143%	92%	(80)	47%	43%	25%
45	161%	104%	(90)	53%	49%	28%
50	179%	115%	(100)	59%	54%	31%
55	196%	127%	(110)	65%	60%	34%
58	207%	134%	(116)	68%	63%	36%
85	304%	196%	(170)	100%	92%	52%
90	321%	208%	(180)	106%	98%	55%
100	357%	231%	(200)	118%	108%	61%
135	482%	312%	(270)	159%	146%	83%
150	536%	346%	(300)	177%	163%	92%
200	714%	462%	(400)	236%	217%	123%
210	750%	485%	(420)	247%	228%	129%
300	1071%	693%	(600)	354%	325%	184%
500	1786%	1155%	(1000)	589%	542%	307%
1000	3571%	2309%	(2000)	1179%	1085%	613%
1600	5714%	3695%	(1600)	1886%	1735%	982%

Appleton: glossary of terms

Glossary of terms from Jay Appleton's The Experience of Landscape^[1].

This is reproduced for the benefit of my students, since the book is out of print (and second hand copies are selling at upwards of £85). I strongly recommend referring to the book itself, if you can get hold of a copy ( perhaps through your library) and this reproduction is only a second best alternative

APPENDIX C Glossary of Terms (To which some particular shade of meaning is attached beyond that normally understood from general usage)
Accessibility	See Penetrability
Animate hazard	An incident hazard in which the threat is posed by some animate agent
Aquatic	(i) Of hazards; an inanimate incident (or impediment) hazard in which the threat is posed by water, (ii) Of surfaces or horizons; a surface or horizon of water, characteristically prospect-dominant
Arboreal	(i) Of refuges; a term used to distinguish refuges on the basis of their substance or fabric, (ii) Of surfaces or horizons; a term used to denote cover by vegetation tall enough to afford refuge 'Arboreal' generally implies refuge-orientation, but the tops of trees, particularly those of upright habit of growth, can act as prospect symbols.
Architectural	A term used of surfaces or horizons composed of artificial structures Architectural surfaces and horizons may be further distinguished on the basis of components (eg walls, roofs, etc) or materials (eg stone, timber, etc)
Balance	The proportion in which different kinds of symbolism are combined in a landscape
Canopy	An opaque covering above a horizontal vista, qv
Carpeted	An 'open' surface or horizon covered by vegetation (eg grass, heather, etc) low enough not to impede visibility under normal conditions
Closed	A term used of prospects in which a view is limited in distance by some intervening screen. A view of short 'fetch', qv
Cloud canopy	A canopy, formed by cloud, covering a sky dado, qv
Contraposition (Adj. Contrapositive)	The juxtaposition of symbols of contrasting type; the opposite of reduplication
Coulisse	Originally a theatrical term denoting scenery which projects from the wings on to the stage; applied in art criticism to any lateral projection from the flanks of a landscape, hence a particular form of interface between voids and masses. Highly significant as a zone of contact between prospect and refuge.
Deficiency hazard	A threat to comfort or survival resulting from some chronic deficiency (eg food) rather than from some incident
Deflected vista	A form of secondary vista in which a deflection of the vistal axis terminates a direct prospect but suggests a continuation of the line of vision in the same general direction
Direct prospect	A view as directly observed
Dominance (Adj. Dominant)	The prevailing influence of a particular kind of symbolism in a landscape, (eg 'prospect dominance', 'refuge dominant', etc)
Exposure	A condition of refuge-deficiency in which the dominant symbolism is that of prospect and hazard combined
Falling ground	A surface sloping downwards away from a vantage-point; a common prospect symbol
False sky dado	A phenomenon similar to a sky dado (qv) in which, however, the bright layer near the horizon is caused by the diffusion of light by particles in the atmosphere impeding rather than facilitating the passage of light
Fetch	The distance over which visibility can be achieved in a particular direction
Fire hazard	One of the categories of inanimate incident hazard
Habitat theory	The theory that aesthetic satisfaction experienced in the contemplation of landscape stems from the spontaneous perception of landscape features which, in their shapes, colours, spatial arrangements and other visible attributes, act as sign-stimuli indicative of environmental conditions favourable for survival, whether they are really favourable or not
Hazard	An incident or condition prejudicial to the attainment of comfort, safety or survival
Hide	A form of refuge which provides concealment from animate hazards. Cf. Shelter
Horizon	A line, not necessarily horizontal, marking the limits within which an object or surface impedes visibility. A horizon is always conspicuous as a secondary vantage-point (qv); it differs from other secondary vantage-points in that its identity depends on its being observed from a particular primary vantage-point
Horizontal vista	A view restricted by conspicuous bounding margins in a horizontal plane
Human hazard	An animate hazard in which the threat is posed by a human agent
Impediment hazard	An obstacle or condition which impedes the threatened party in securing an environmental advantage by restricting his freedom of movement (e.g. a wall, fence or river)
Inanimate hazard	An incident hazard in which the threat is posed by some inanimate instrument or by the onset of some condition not determined by any animate agent (e.g. a storm or earthquake)
Incident hazard	A hazard which seems to be occasioned by some incident rather than by some condition
Indirect prospect	The imagined view from a secondary vantage-point, qv.
Instability hazard	An inanimate incident hazard resulting from instability (eg a landslide)
Interface (Prospect-Refuge Interface)	The zone of contact between those parts of the environment which are visible from a vantage-point and those which are not, or between prospect-dominant and refuge-dominant areas. See Coulisse
Interrupted panorama	A panorama broken by obstacles insufficient to destroy the impression of a single landscape. Cf Multiple vista.
Inversion	The association of one kind of symbolism with an object or situation normally associated with another; eg in nocturnal landscapes, when the usual symbolism of prospect in the sky (light) is replaced by that of refuge (darkness)
Involvement	Participation in any activity or experience which implies a functional, strategic or perceptual relationship between an observer and his environment
Lateral vista	See Offset Locomotion hazardAn incident hazard resulting from movement by the threatened party, eg a fall
Magnet (Adj. Magnetic)	A part of the landscape which attracts the eye of the observer. The adjective 'magnetic' can be applied to a point, line, area, etc.
Meterological hazard	An inanimate incident hazard in which the threat is posed by some meterological phenomenon (eg wind, rain, snow, etc)
Multiple vista	A view resulting from two or more breaches in an opaque screen, where the efficacy of the screen is sufficient to destroy the impression of a continuous panorama Cf Interrupted panorama
Naked	A term applied to an open surface or horizon uncovered by vegetation (eg consisting of rock, sand, asphalt, etc)
Nebulous	(i) Of apparent surfaces or horizons consisting of dust or water particles suspended in the atmosphere (eg fog, smoke, cloud, etc); (ii) Of refuges formed by such substances
Non-human hazard	An animate hazard in which the threat is posed by an animalother than a human_
Offset (lateral vista)	An indirect prospect which results from an apparent breach in the confining flanks of a vista, suggesting the opportunity to achieve a prospect approximately at right angles to the vistal channel
Open	A term used of surfaces or horizons relatively free from impediments to vision and therefore prospect-dominant See 'Naked' and 'Carpeted'
Panorama	A view in which breadth is a dominant characteristic
Peephole	A view restricted in both horizontal and vertical planes, as in a window, rock arch, etc
Penetrability (Accessibility)	The property of the margin of a refuge which appears to offer easy access (eg by an opening, staircase, shaded edge, etc)
Primary vantage-point	A place from which a direct prospect is observed
Prospect	(i) A view, (ii) An environmental condition, situation, object or arrangement conducive to the attainment of a view.
Prospect-refuge theory	The theory that the ability to see without being seen is conducive to the exploitation of environmental conditions favourable to biological survival and is therefore a source of pleasure
Reduplication	The use of two or more symbols of similar kind to reinforce each other (eg a cottage in a wood, both being refuge symbols)
Refuge	An environmental condition, situation, object or arrangement conducive to hiding or sheltering. See 'Hide' and 'Shelter'
Secondary panorama, vista	An indirect prospect (qv) of panoramic or vistal form
Secondary vantage-point	A place or object, usually elevated, which suggests a further extension of an observer's field of vision See 'Indirect prospect'
Shelter	A form of refuge which provides protection against inanimate hazards Cf 'Hide'
Sky dado	A horizontal vista formed by a layer of bright, clear sky between a horizon and a cloud canopy, qv
Terrestrial	A term used of surfaces or horizons consisting of solid as opposed to fluid substances Cf 'carpeted' or 'arboreal' with 'aquatic' or 'nebulous' surfaces or horizons
Texture	A property of a surface deriving from the material of which it is composed, chiefly apprehended by the manner in which it reflects light (eg 'naked', 'arboreal', 'aquatic', etc)
Token symbols	Symbols introduced in a miniature or inconspicuous form to complement a dominant symbolism of a different kind
Value	The capacity of an environmental situation, condition, object or arrangement to communicate a suggestion of prospect ('prospect value'), refuge ('refuge value') or hazard ('hazard value')
Vista (Adj Vistal)	A view restricted by conspicuous bounding margins, generally vertical or near-vertical; but cf Horizontal vista, Sky dado

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1. Appleton, J., The Experience of Landscape. 1986, Hull: Hull University Press.

ICT

ICT: Information and Communication Technology.

See this Wikipedia entry for more detail.

Chreo...what?

Because of where my interests have led me, I am often asked to explain the word "chreostochastic". Here is a quick attempt to which I can direct future requests.

"Stochastic" describes a process where chance decides the outcome of an event within limits set by the preceding event. Imagine that you close your eyes, spin round on the spot, and then jump. Your landing point will be, let's say, somewhere within a metre of your starting place. Keep your eyes shut, spin again, jump again. Which way you jump each time is roughly random; how far you can jump is limited by your own strength and balance; and where the jump of a given strength and direction will take you is decided by where the last jump left you. That last fact makes this process of jumping a stochastic one. (Mathematicians call your series of jumps a "random walk".)

"Chreodic" means "channelled". Imagine that your bizarre series of spinning jumps with closed eyes, your random walk, takes place within a grassy furrow whose sides slope gently upward to either side of you - perhaps to a height of three or four metres, at an angle of thirty degrees or so. Beyond the slopes lie other, parallel furrows. Your series of jumps may, in theory, take you up one of the slopes and over the top into the next furrow - but gravity ensures that, once on a slope, you are more likely to jump down than up, and so more likely to stay in the furrow than to leave it. Your random walk is being channelled – it is chreodic. If you ever do move over the top into the next furrow, the same reasoning is most likely to keep you there rather than returning.

Combining the two ... a chreostochastic process is one in which each step is probabilistic, but from a starting point decided by the previous step, but within partial constraints which cause it to tend in one direction without actually preventing other outcomes.