Prezi 4 scale

[tomcrane]

spatialScale and temporalScale => model

[JulieWinchester]

This is a run at providing explicit definitions of the association for spatialScale, and is independent from the question of whether we hard-wire the UnitValue value as meters and seconds for these properties. What do you think?

[mikeapp]

"distance between": I think of pixels as an area, not a point. I might suggest: "expectation for the physical area represented by each individual pixel"

[JulieWinchester]

This is fair, and I wondered if someone might have different thoughts on that. I think I'm fine either way. My reasoning for using distance between is because I was modeling my approach off of computed tomography images (XRay-CT, MRI, etc.), which is the domain I'm most familiar with where physical distance and pixels are tightly linked. For CT, each pixel is treated as a coordinate location and the pixel color/value is an indication of the intensity of the signal(s) at that particular point in space. Because of that, in DICOM and other standards, physical distance is defined as being the length between the center of adjacent pixels. But I used that definition not just here in the overview as an example for X-Rays but also in the model explicitly, so I'm fine if we want to switch to a definition more based on pixels as area.

[JulieWinchester]

Suggestions for opening up the language to other units in a future extension.

[JulieWinchester]

Suggested change

A single UnitValue that defines a real-world scale factor for the coordinate units of a Canvas or Scene. For a Canvas, this defines the physical distance between adjacent units horizontally and vertically. A Canvas with a `width` of 5000 and a `spatialScale` with `value` 0.00008 represents a physical space 0.4 metres wide. For a Scene, this defines the physical distance corresponding to the XYZ coordinate units, or in other words, the physical distance length of a unit vector in the 3D coordinate space. The value of `unit` _MUST_ always be `m`, i.e., metres.

A single UnitValue that defines a real-world scale factor for the coordinate units of a Canvas or Scene. For a Canvas, this defines the physical distance between adjacent units horizontally and vertically. A Canvas with a `width` of 5000 and a `spatialScale` with `value` 0.00008 represents a physical space 0.4 metres wide. For a Scene, this defines the physical distance corresponding to the XYZ coordinate units, or in other words, the physical distance length of a unit vector in the 3D coordinate space. The value of `unit` _MUST_ be a length unit. In this specification, the only length unit defined is `m`, i.e., metres. Unless other values are defined externally as an [extension][prezi30-ldce], the value of `unit` _SHOULD_ always be `m`.

[JulieWinchester]

Suggested change

	{
	"type": "Scene",
	"spatialScale": {
	"type": "UnitValue",
	"value": 22.0,
	"unit": "m"
	}
	}
	{
	"type": "Scene",
	"spatialScale": {
	"type": "UnitValue",
	"value": 22.0,
	"unit": "m"
	}
	}

[JulieWinchester]

Suggested change

A single UnitValue that defines a multiplier or scale factor for the `duration` property of a Container, indicating that one second in "Container time" represents some other real world duration. A Canvas with a `duration` of 450 seconds and a `temporalScale` with `value` 1000 represents a real-world duration of 450,000 seconds (5.2 days), for example a time-lapse video of a growing plant. The value of `unit` _MUST_ always be `s`, i.e., seconds.

A single UnitValue that defines a multiplier or scale factor for the `duration` property of a Container, indicating that one second in "Container time" represents some other real world duration. A Canvas with a `duration` of 450 seconds and a `temporalScale` with `value` 1000 represents a real-world duration of 450,000 seconds (5.2 days), for example a time-lapse video of a growing plant. The value of `unit` _MUST_ be a time unit. In this specification, the only time unit defined is `s`, i.e., seconds. Unless other values are defined externally as an [extension][prezi30-ldce], the value of `unit` _SHOULD_ always be `s`.

[JulieWinchester]

Suggested change

	"type": "Canvas",
	"temporalScale": {
	"type": "UnitValue",
	"value": 1000,
	"unit": "s"
	}
	}
	"type": "Canvas",
	"temporalScale": {
	"type": "UnitValue",
	"value": 1000,
	"unit": "s"
	}
	}

[JulieWinchester]

Suggested change

The value of `spatialScale` is a `UnitValue` (ref) that always has the value "m", i.e., metres. If source size metadata is machine readable (or parse-able) in other measurement systems (e.g., feet and inches) then it should be converted to metres for use in `spatialScale`. Publishers may wish to present the original given measure (e.g., from catalogue metadata) in a `metadata` field for context.

The value of `spatialScale` is a `UnitValue` (ref) that has as a value a length unit. This specification defines only one length unit, "m", i.e., metres, though others may be defined externally as an [extension][prezi30-ldce]. If source size metadata is machine readable (or parse-able) in other measurement systems (e.g., feet and inches) then it should be converted to metres for use in `spatialScale`. Publishers may wish to present the original given measure (e.g., from catalogue metadata) in a `metadata` field for context.