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popol

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Posts posted by popol

  2. Posté(e) · Report reply

    j'avais gardé ça de coté: 

     

    Quote

    There are a couple of things to keep in mind when dealing with units (especially System Units setup).

    Precision!
    Max always manipulates data internally in generic units, stored in single precision floating point format. This means that there are physical limits of how fine and how large the values can be.
    If you are modeling the fine mechanics of a watch, you would probably go with 1 Generic Unit == 1 mm, which gives you lots of detail when dealing with sub-mm values. Obviously, the whole model would not be larger than couple of centimeters, so you are safe in both directions.
    On the other hand, modeling an entire city would be an overkill at these same settings, as you never model with such precision all the crews in the construction of every window in every building. At the same time, if you are designing a sequence including detailed characters in that city, using 1 Generic Unit == 1 foot would be a disaster as you wouldn’t be able to get enough detail in your characters. For example, if you are using a spline to model a whip the character is holding, and want to use the NormalizeSpline modifier on top of it, you will discover that the lowest Generic Units value allowed by the modifier is 1.0, which does not let you apply it effectively to a whip modeled at 1GU=1 foot! Even worse, some plug-ins like SimCloth for example will be unable to solve the cloth collisions at such settings because of lack of decimal precision in the manipulated vertex data, boolean operations between small objects will always fail etc.
    As if that is not bad enough, viewport navigation can become unusable when working at the wrong scale! Z clipping becomes difficult without using manual clipping planes. Rotating the mouse wheel one tick can zoom past your tiny character as the setup is made for a large city and not for bugs in the street…

    So in a word, you have to consider the relative size of the objects and the minumum and maximum detail you are going to deal with.

    There is an additional problem with loosing precision with increasing distance from the origin. As the position values grow, the ability of the application to represent values with floating point precision decreases. This is what the Accuracy field in the System Units setup is for. It lets you enter a distance to the origin and see what the finest possible detail would be.

    Normally, when creating a model of the Earth (e.g. 1GU = 1000 km) , you can forget about representing its population at the same time. :slight_smile:

    Data exchange.
    When importing data, for example an architectural model or a model of a car made in AutoCAD or another external application, you want to end up with usable size.
    Let’s say you have a 3D model of a house designed in AutoCAD using 1 Generic Unit as 1 cm, which is about 40 meters (4000 cm) wide.
    And you have a detailed model of a VW Beetle also made in AutoCAD, but this time at the typical engineering scale of 1 Generic Unit = 1 mm. The length of the model would be 4080 mm, or 4.08 m (an old year 1970 1302 model). Obviously, the house is 10 times wider than the car, but both have about the same size in Generic Units - around 4000!

    If you would import the two models into a 3ds max scene which is set to 1 Generic Unit = 1 cm, the house will transfer the data 1:1 from AutoCAD, giving you exactly the same Generic Units values in the max scene, but the car model would be imported 10 times larger!
    If you would import the car model into a scene with 1 Generic Unit == 1 mm and then merge the saved scene with the house that was imported at 4000 Generic Units = 4000 cm, the model will land into the millimeters scene as 40000 units = 40000 mm = 4000 cm = 40 m, and the car will fit in the garage! (Same in the other direction).
    So the knowledge of the System Units of both files helps 3dsmax scale the values when merging to give you objects that fit together despite the differences in the assumed meaning of the Generic Units used to store the data internally…

    As you know, trying to mass-rescale the units after the fact can lead to problems, but for mergin single ASSETS into a scene the system really works. It is a good idea to think about the units before creating a single polygon, as it could make the difference between creative heaven and fighting-the-scene hell!

    User Interface and Workflow
    The “Display Units” settings are just an UI layer that converts the internal Generic Units representation into something a human can understand better. They are NOT used to match data between files and don’t affect the way the data is stored, but can affect the way the data is entered. For example, if in the above example you were interested in putting a small block together made of instances of the house and your system units were still set to 1GU==1mm, you would have to enter large numbers with lots of zeros just to move the house a steet away. Changing the UI to display Metric> Meters will show you a house that is 40 m wide, and to move it 60 meters to the side you would have to enter only 60 in the Transform Type-In, not 6000 !
    Also, these settings can be a life saviour when dealing with international projects where the two sides use different systems (SI metric vs. Imperial). Let’s say a model for a movie set was developed in Canada using meters and shipped to a company in Hollywood using feet and inches. The guys there want to do some work on the model but have no idea what the values mean in the real-world measurements they are used to.
    Simply changing the Display Units to show Feet and Decimal Inches will turn a 40 meters house into a 131’2.803" house without touching any data internally. The guys can manipulate the model and UNDERSTAND how big it really is without learning the metric system - max does the math for them!

    I hope this helps a bit. I am sure I have just scratched the surface.

    Bobo

     

    Nicolas Caplat et Troadegrafix reacted to this

  5. Posté(e) · Report reply

    Pour les curieux :) 

     

    Quote

     

    SideFX is proud to present the Houdini HIVE Paris!

    Join us for an amazing day of educational presentations by top Houdini artists - from firms including MPC, Ubisoft, Nki - and SideFX! More info here: https://sidefx.co/2JyRPco

     

    https://www.eventbrite.com/e/houdini-hive-paris-tickets-61792362620?fbclid=IwAR39UYP3-4FUhHQmCEpJ0BVIc5wrHXRxUA-yxx0iStvAcwfuySinWTUWgDc

    Nicolas Caplat et SugaR reacted to this

  14. Posté(e) · Report reply

    Bah on a toujours la même première impression quand on commence à bosser sur un nouveaux softs, perso quand j'ai attaqué Max j'ai passé ma première semaine en PLS sous le bureau : D.

    Quote

     des petits trucs par ci par là qui en font un soft certes surpuissant, mais pas franchement simple à apprendre , pas franchement artist-friendly je trouve :)

    C vrai, sidefx fait de gros effort là-dessus mais c pas encore ça.

    2 hours ago, Nicolas Caplat said:

    quand tu drag la sortie d'un node pour en ajouter un, la liste des nodes n'apparait pas automatiquement ...

    Ta juste a appuyé sur tab, si sa poppais automatiquement ce serait un vrai bordel . sinon click droit sur l'output et tu sélectionnes ton onde 

    Nicolas Caplat reacted to this

  16. Posté(e) · Report reply

    4 hours ago, Nicolas Caplat said:

    Même avec le prix des licences & des updates ? ;)

    Ouai ça peut faire flipper, mais bon t'a une solution ultra  complète. Et si on veut l'équivalent sous Maya ou Max le prix grimpe a vitesse grand V ....

  23. Posté(e) · Report reply

    Quote

    L'avantage de la souris c'est que lorsque tu es positionné sur un endroit, le curseur ne bouge plus, mais avec le stylet le curseur bouge toujours un peu à cause des mouvement de ton corps par exemple. Rendant par la même occasion la sélection de précision très complexe.

    C vraiment une question d'habitude, ça fait des années que je tricote du vertex au stylet et c tout a fait gérable.

    Choupi reacted to this
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