Importing boats - real problems with units scale

[Nats]

Hi Ive done a 3d model with the units in mm as you would expect with me working in the UK as all architects work in mm here.

 

But I am trying to merge some max boat files and they are coming in massive. Fine I think, as the ship was probably done in the US, so I select change system units to inches to suit suit and then the boat comes in really small. I cant understand it.

 

So I go into the original boat files themselves and a dialog comes up saying units are differnet so I select 'change system unit to file units' (inches) and I go into the model and the system units are in inches and the display units are set as generic units for some reason? When I check the model size using measure tool the scaling seems to be far too large - for example a flag on a U boat is scaling at 3m across when it should be probably around 1m across). So I have no idea whats going on.

 

What is the process for merging such vehicles etc into architecctural models, where the units are in mm so, they scale correctly? I am used to scaling engineers drawings down by 1000 here in the UK - as engineers always draw in meters not mm so perhaps I need to scale these models down by 25.4 to get the inches into mm? Dunno. Anyone?

 

Any help greatly appreciated as I am new to this Max units conversion thing and this has me completely lost.

Edited July 15, 2010 by Nats

[datacrasher]

Nigel

make sure you are using the same units as your previous scene because sometimes your objects/models will come in bigger or smaller depending on the units setup once merged

[Nats]

Yeah but if I am trying to import a boat which is drawn using inch system units and generic display units, how do I get that into my architectural plan at the right size - which has system units of mm? Do I have to do something in the original file first before I import it? I would have thought that the model would have just intelligently rescaled itself correctly on merge but it obviously hasnt.

 

I have looked at a few car models I got off the internet as well. Again they were drawn in inch system units and generic display units. Without changing the units at all when I measure across the car width I get a measurement of 367? Whats that supposed to be? You would think that it would be inches - but that would work out that the car is 9m wide so its not inches. So whats is the model drawn in? And how would I get this to be scaled in mm? The car should be around 1.5m wide in reality.

 

Any help appreciated I am completely lost here.

[datacrasher]

Lets says “your units are set to us standard” and you have modeled it in center meters they need to be the same all the same you cannot just change the units setup when you merge the file because this your model will always come in big or small depending on your unit scale if you scale your model up or down the model will look on out place and out of kilter. So before your start modeling you need to make sure all the display and system units are the same as your previous scene.

The problem with the models on the internet is that they never give you the unit scale so you need to open the car model in max and check the units. When you restart max then you will need to change the units so it is the same as the car. When you have completed the model then the car and the model are at the same units and they will merge/import as the same

[mattclinch]

Lets says “your units are set to us standard” and you have modeled it in center meters they need to be the same all the same you cannot just change the units setup when you merge the file because this your model will always come in big or small depending on your unit scale if you scale your model up or down the model will look on out place and out of kilter. So before your start modeling you need to make sure all the display and system units are the same as your previous scene.

 

The problem with the models on the internet is that they never give you the unit scale so you need to open the car model in max and check the units. When you restart max then you will need to change the units so it is the same as the car. When you have completed the model then the car and the model are at the same units and they will merge/import as the same

 

i'm sorry, but i don't agree with this at all.

 

display units are completely irrelevant in this case. they are just a visual aid.

only system units matter. 1 'unit' of distance in max is equal to a chosen real-world measurement.

if everything is modelled to scale, regardless of the system unit (metres, millimetres, inches, feet, etc) then merging files between each other should keep everything in the same scale.

 

example. I have one file with system units at 1 unit = 1 foot. display units at generic. in that scene i model a box 1x1. my box is therefore 1ftx1ft. i can choose display units to be inches and it will tell me the box i have just modelled is 12inches x 12 inches, or metres and it will be 0.305m x 0.305m. essentially the box still measures 1 foot. i save that file.

 

another file is 1 unit = 1 metre. display units as generic. in this scene i model a 1x1 box. this box is therefore 1m x 1m. if i now import the previous file i will have my 1x1 box and my imported box will be 0.305x0.305 as max is smart enough to realise that each unit in the other file is only 0.305 units in this one. essentially is knows the reltionship between feet and metres.

 

essentially if both scenes are modelled to a real world system unit and to scale, you should be able to merge between different files regardless of the system units and retain accurate scale.

[datacrasher]

I think you should learn to spell correctly if you do the tutorials and read the manuals that come with max then you would know that what I am saying is correct and they are not irrelevant it’s a fact when using any animation program. No max is not smart enough it’s a program like any other program all programs make mistakes,

When you merge a scene in different display and system unit they will completely come out different sometimes big and sometimes small

[Nats]

I agree that the display units setting should have no bearing on the actual model size it simply affects how the displayed measurements are depicted, its only the system units setting that determines the size of the model ie whether its drawn in inches or m or mm. When you think about it you are modelling everything in real size anyway - so it doesnt matter whether you are using inches or mm to model it. Two identical Mazda cars one modelled in Imperial and one in Metric units should surely be identical when placed side by side in the same file shouldnt they? If you merge the Imperial one into the metric file and select 'keep file units' the cars should come out exactly the same size shouldnt they?

 

Anyway as an experiment I have just opened up the E-boat max file I have which has its file system units set in inches. And when the dialog came up saying the file has different units from my normal max (which I have set at mm usually) I selected 'use file system units'. I then measured the length of the MG42 machine gun on the boat which should be around 1220mm long (48.8 inches) in real life and in the model it measures 381 generic units, 9649 mm and 379 inches (depending on what I choose for the display units) neither of which is correct. However a King George ship model I had a look at, which was again modelled in inches, measures correctly. I have also looked at some of my car models from the internet and some of them also are scaled wierdly as I mentioned above scaling at 9m wide. Yet others scale correctly (generally the metrically modelled ones).

 

So I am now wondering whether some of these internet files have somehow been randomly scaled at source? Perhaps it was done deliberately to make them relatively unusable I dont know? Seems a daft thing to do to me - put models on the internet but have them modelled as a completely unrealistic size? Has anyone else come across this kind of thing before?

Edited July 15, 2010 by Nats

[Dave Buckley]

I think you should learn to spell correctly if you do the tutorials and read the manuals that come with max then you would know that what I am saying is correct and they are not irrelevant it’s a fact when using any animation program. No max is not smart enough it’s a program like any other program all programs make mistakes,

 

When you merge a scene in different display and system unit they will completely come out different sometimes big and sometimes small

 

stop talking about display units and read the manual yourself, display units is completely irrelevant to this situation

 

from the help file which you say you have read:

 

"It is important to note the distinction between System and Display units. Display units only affect how geometry is displayed in the viewports. System units determine the actual scale of geometry. For example, if you import a DXF file (unitless) containing a 1 x 1 x 1 Box, 3ds Max Design could import the box’s dimensions in inches or miles, depending on the System unit. This can have a significant impact on your scene, which is why you should always set up the system unit before you import or create geometry."

 

And if we are talking about grammar, I suggest you don't. Before correcting others i suggest you go and check the homepage of your website first and correct that.

 

Sorry Nats, didn't mean to hijack the thread, it just annoys me when people respond in a rude manner.

 

Perhaps this another reason why one shouldn't ever use the scale tool in Max

[mattclinch]

...you have modeled it in center meters...

 

...I think you should learn to spell correctly...

 

ditto.

but please, for future reference, what did i spell wrong?

sorry for trying to help, but i consider the information you are giving out to be, in my opinion, inaccurate and misleading.

Edited July 15, 2010 by mattclinch

[Dave Buckley]

from my private messages, from Datacrasher

 

"who are you telling what to do? ****ing fool i have help a lot of people in different fourms i don't care about my gammar at least i can spell without making mistakes thanks. What i am saying is correctly and it has nothing to do with FBX thanks"

 

if you don't care about your grammar then don't tell other people to learn to spell, that's all i was saying.

 

you can spell without making mistakes? - see matt's post above - center meters or did you mean centimetres?

 

who mentioned FBX? - i'm guessing you can't read now either?

 

i have no doubt you have helped a lot of people in other forums but you are really not helping people here by giving inaccurate advice and then being adamant that you are correct. you even admitted in another thread that you sometimes make mistakes.

 

now can we get this thread back on subject

[Nats]

From the manual:

 

Generic Units (The default.) A Generic or “system” unit in 3ds Max is equal to one inch. You can treat it as an arbitrary unit of your own definition, unless your scene uses features that depend on real-world measurements, such as photometric lights, Use Real-World Scale for bitmaps, and so on.

Warning If you are modeling an object that includes details whose dimensions are very much less than one inch, treat the Generic unit as an arbitrary unit that is smaller than one inch: for example, 1 unit = 1/50 of an inch. Otherwise, you might encounter problems with your model that are due to roundoff error.

 

 

This is why I now think most of these boat models are right off in terms of scale. I bet most of the people who modelled these things just used bitmap references off the internet that werent at any particular scale or were scanned in, and just modelled straight off those. The fact that 3dsmax is defaulted to 'generic units' must surely mean that most people are going to model a generic model that is not to a particular scale (even though they do say that the generic unit is 1 inch). Personally, coming from an architectural background, I cannot believe anyone doing a model would do it 'not to scale' (as I put on my architectural sketches). Surely the very fact you are trying to make a real lifelike model means you should be doing it an accurate size. I mean whats the point modelling a Ferrari at 40m long? Seems completely daft. Anyway it looks like I am going to have to get some data on the sizes of these boats and scale them to suit. What a pain.

[Ricardo Eloy]

Ok, peeps, let's keep things polite, alright?

@Datacrasher, the PM system is not here for people to send offensive messages so no one will know. It's here to facilitate connections between people willing to help each other. Keep that in mind the next time you feel like being rude again, right mate?

And, just for the record, Dave and Matt are correct about the units.

[Dave Buckley]

From the manual:

 

Generic Units (The default.) A Generic or “system” unit in 3ds Max is equal to one inch. You can treat it as an arbitrary unit of your own definition, unless your scene uses features that depend on real-world measurements, such as photometric lights, Use Real-World Scale for bitmaps, and so on.

Warning If you are modeling an object that includes details whose dimensions are very much less than one inch, treat the Generic unit as an arbitrary unit that is smaller than one inch: for example, 1 unit = 1/50 of an inch. Otherwise, you might encounter problems with your model that are due to roundoff error.

 

 

This is why I now think most of these boat models are right off in terms of scale. I bet most of the people who modelled these things just used bitmap references off the internet that werent at any particular scale or were scanned in, and just modelled straight off those. The fact that 3dsmax is defaulted to 'generic units' must surely mean that most people are going to model a generic model that is not to a particular scale (even though they do say that the generic unit is 1 inch). Personally, coming from an architectural background, I cannot believe anyone doing a model would do it 'not to scale' (as I put on my architectural sketches). Surely the very fact you are trying to make a real lifelike model means you should be doing it an accurate size. I mean whats the point modelling a Ferrari at 40m long? Seems completely daft. Anyway it looks like I am going to have to get some data on the sizes of these boats and scale them to suit. What a pain.

 

1 generic unit = 1 inch by default purely because the default system unit after an installation of max is set to 1 unit = 1 inch, if you change system units to 1 unit = 1 mm then 1 generic unit would be equal to 1mm, or so i believe.

 

cheers rick

[Ricardo Eloy]

Just for the record, I never change the system units. I mean, since I can already "speak" metric using the display units, I simply don't see why I would need to change the system units (except if I don't want max to create things every 2.54cm, in that case I change it to 1 unit = 0.025 meters to round things down a bit). From my short experience, sticking to the 1 unit = 1 inch method gives you greater control and accuracy when it comes to reactor calcs, lighting and even importing from CAD.

Cheers

[neko]

wow - how to make friends and build professional relationships on the internet.

 

the thread got there in the end though, which is usually the case (thankfully).

[-MerlyN-]

Just for the record, I never change the system units. I mean, since I can already "speak" metric using the display units, I simply don't see why I would need to change the system units (except if I don't want max to create things every 2.54cm, in that case I change it to 1 unit = 0.025 meters to round things down a bit). From my short experience, sticking to the 1 unit = 1 inch method gives you greater control and accuracy when it comes to reactor calcs, lighting and even importing from CAD.

Cheers

 

I totally agree with Rick here. Leaving the System Unit at its default creates the least pain in the long run. Sometimes I do set it to 1unit=1mm to get the maximum out of accuracy or when I need to model tiny things to scale (ever tried to model a 2mm screw with units set to inch? ^.^) but I often end up having to do a lot of experimenting as suddently lighting units and units in scripts get a life of their own.

 

And yeah, a lot of objects on the net, especially the free ones, seem to be modeled to no specific scale at all.

I often thought it would be nice, if the scale and unit setup was shown in the file preview or even better in the file description before you download...