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wrightyp100
11-28-2017, 08:34 AM
Just a quickie, but why does lightwave change Km to Mm?

Is it just the way it copes with huge sizes/distances?

Cheers :)

Sensei
11-28-2017, 09:12 AM
Just a thought. In different countries coma and dot are treated differently.
https://en.wikipedia.org/wiki/Decimal_mark
If you use 1.000 km and 1,000 km, country and language settings in OS and application, play a role how to translate coma and dot.

BTW, you can use math operations in text fields.
f.e. you have 1000 m
append 1000*30 m,
and it'll change to 30 km.
f.e. you have 1 Mm
divide by 1000,
and it'll change to 1 km.

magiclight
11-28-2017, 09:23 AM
It displays the value as the "shortest" value, 10mm looks nicer compared to 0.00001km, if I remember correct you can select if you want it to be displayed in default unit always or as the shorest value.

MonroePoteet
11-28-2017, 09:30 AM
I'd guess it has to do with the limit of significant digits in the binary 32-bit floating representation. Although LW is a 64-bit application, it still uses the Binary32 standard (sometimes called Float32) to store numbers internally. This IEEE standard provides for between 6 and 9 significant digits and may lose precision in low-order digits, so it may not be able to represent (for example) 1,234,567,890 meters accurately. I'd guess that LW changes the units so we users don't expect a granularity which can't be accurately represented in Binary32. For example, they can guarantee that 1.2345 Mm may be stored accurately with no expectations of exact digits beyond those shown, but LW can't guarantee that 1,234,567,890 meters will be stored accurately using Binary32.

Just a guess, though! :)

mTp

wrightyp100
11-28-2017, 12:45 PM
I'd guess it has to do with the limit of significant digits in the binary 32-bit floating representation. Although LW is a 64-bit application, it still uses the Binary32 standard (sometimes called Float32) to store numbers internally. This IEEE standard provides for between 6 and 9 significant digits and may lose precision in low-order digits, so it may not be able to represent (for example) 1,234,567,890 meters accurately. I'd guess that LW changes the units so we users don't expect a granularity which can't be accurately represented in Binary32. For example, they can guarantee that 1.2345 Mm may be stored accurately with no expectations of exact digits beyond those shown, but LW can't guarantee that 1,234,567,890 meters will be stored accurately using Binary32.

Just a guess, though! :)

mTp

Cheers guys,

the reason being I made (what I think is a scale model of the earth) and put a scale moon at over 300,000km away.

Putting someting 400km above the 'earth' looks correct and it all looks to scale (and is still represented as 'Km'), i was just interested as to why it changed from Km to Mm.

Its just so if the person I was doing it for sees it, I will have an answer for them :)

Surrealist.
11-28-2017, 01:32 PM
It is just how LightWave basically automatically assumes if you put in a high number, you want to jump up to the next display level. And it does this based on your Options settings, in the General tab, under Unit System and Default Units.

So basically if you are in Meters and you input 1000 it will display 1km. And if in km 1000 will display 1Mm. This is so you can start using that level of display rather than taking up unnecessary space with 00000. As magiclight points out.

wrightyp100
11-28-2017, 01:48 PM
It is just how LightWave basically automatically assumes if you put in a high number, you want to jump up to the next display level. And it does this based on your Options settings, in the General tab, under Unit System and Default Units.

So basically if you are in Meters and you input 1000 it will display 1km. And if in km 1000 will display 1Mm. This is so you can start using that level of display rather than taking up unnecessary space with 00000. As magiclight points out.

Great stuff guys. Thanks.

Glad it was an easy one :) :) :)