Help:Objects to indicate scale

A photo of some rocks. Sadly, rocks are pretty fractal, so there is no easy way to know if this picture is ten centimeters or ten meters across. Fortunately there is a white object to indicate scale. It's a bit overexposed, though, and it's not clear what the object is...

In some photos, the size of the scene is not clear. Including an object of a familiar size can give a sense of scale.

At this point we run into cultural differnces. Commons is a global project, and, say, the American quarter which is familiar Americans is not necessarily recognizable worldwide. This is why we have the template {{NoCoins}}. We want context-free objects, which everyone worldwide is likely to recognize, and know the size of. Worse, we need to use object which people of the future are likely to recognize and know the size of.

Countries by current metrication status:

 

Complete

 

Almost complete

 

Partially complete

 

Little adoption

The preferred solution is a metric scale. The metric system is used almost everywhere worldwide. You may already carry an object with a metric scale marked: if not, there are a number of lightweight options.

Potential problems

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  Paperclips come in multiple sizes, and not everyone uses them, so they are not a good choice
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  Binder clips and batteries come in various sizes, though in this case the uploader has laboriously specificed the dimensions of the battery used for scale.
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  Are the gradations are identifiable? The lines on this ruler probably mark millimeters...
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  Some people know what size obsolete computer storage formats are, and can thus see the scale of this ink bottle...
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  ...but everyone else needs a scale.
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  A human hand for scale is OK as long as you don't need great precision; hands vary in size.

Scale cards

A card with a scale marked on it is light and can make a convenient scale.

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  A plastic scale card marked with a 1-cm checkerboard
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  Specialized diameters scale card.
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  Multitools almost always include rulers. Even this tiny little wallet-card multitool has a scale marked in centimeters along the upper edge (more visible at other angles and lighting)
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  This pocket toolbox, which weighs the better part of a kilogram, does at least have a ruler marked on it.

Measuring tapes and rules

Measuring tapes can be quite lightweight.

• the paper tapes Ikea and the like gives away are very light, if not very durable.
• keyring metal tape measure. Often given away as a promotional item, or try hardware stores; these have a very light and thin metal rule. Companies that print artwork on any promotional merchandise, from t-shirt and pens up, often sell these.
• pushbutton flexible tape measure: a narrow ~5cm diameter round plastic reel, containing a 150cm PVC-coated fiberglass tape; the center of the reel will have a pushbutton, and if you push on it the tape will instantly retract (there's a spring inside, usually metal, just like the spring in a metal measure, but smaller; images). These tapes are lighter than a similar length of stiff metal tape, and they can measure circumferences. These are most easily found in sewing stores.
• still in the sewing store, buy a loose (no-spool) sewing tape, and if needed, lighten it by cutting off only the first 10cm or so. The hole in the end will be handy for securing it.

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  Paper tape, Ikea etc. give metric/dual ones away.
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  Keyring tape measure.
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  Cut a section of a flexible tape, or buy a retractable pushbutton one (Commons has no image of a pushbutton tape)
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  A PVC-fiberglass tape used to indicate scale
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  A rigid plastic ruler used to indicate scale
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  Meterstick and cricketbat

Low-context objects

A pencil is an object with pretty standard diameter, familiar to more people than any coin, and currently almost a context-free object for the literate. You could buy ones with ruler gradations marked on them, or mark it yourself. See Category:Images with pencils to indicate scale

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  Pencils mostly come in a standard size
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  You could also mark or carve a scale into a pencil.

Make your own scale

Finally, you can make a scale on whatever objects you carry around anyway. A suitable pen, soldering iron, hot knife, dremel or engraving tool will put a scale on almost anything, from a water bottle to a shoe sole. Bag and backpack straps can be marked off with a permanent laundry pen. Waterproof sticking tape, stuck to a water bottle or something else you have to hand, can also be marked off. I've seen walking sticks taped it at regular increments with a variety of colors of good electrical tape. Tape doubles as a useful material for repairs.

For fieldwork

If you are doing some types of fieldwork, you may already have a scale on your equipment.

• Some compasses have rulers marked on the side. The odd GPS has markings, too.
• your map scale, if you have a paper map
• your tripod leg will often have a scale, if you are carrying one

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  This geological compass has a rule marked on it
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  This much cheaper baseplate compass and chart plotter does too.
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  This section of the map gives a usable scale. We can easily calculate that each of the 10km segments in the scale bar is 1.6cm long.