Layers in SU vs. Layers in CAD

Am I suppose to use the layers in SU the same way I use layers in my Datacad program? Also is it best to put the different floors on different layers so you can turn of the second floor layer to work on the first floor?

No. Layers in SketchUp are only used to control the visibility of entities. You can put floors on different layers but you need to group the geometry to provide separation. See the Help article here: http://help.sketchup.com/en/article/3000122

When you are working in SketchUp, follow two basic rules. Leave Layer 0 active at all times. Leave all edges and faces on Layer 0 and only assign groups/components to other layers.

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DaveR thank you, I am an architect so in a typical model for a 2 story residence, how many layers should I have? 1Deck, 1 Ext Walls, 1 Int Walls, etc or is that too many.

You need as many layers as you need. It depends upon how you want to organize your model and what you need to show. You might create layers for floors, reflected ceiling plans, windows,doors, appliances, and fixtures.

You should probably take a look at the work of Architect Nick Sonder. He has some great info that should get you going. He has a book done with Matt Donley that you should check out. http://www.sketchupbook.com/

Thanks again!

Do not approach basic model organization in terms of Layers.

Organize the model by building one logical portion of the structure at a time.
Make the first portion a Component before you proceed to model the next logical portion of the model.
Make that portion a Component before beginning to model the next logical portion of the model.
And so on … until the completed model is an assembly of Components with no raw geometry left behind.

Assigning the Components to various Layers enables you to control their visibility.
The use of Scenes enables you to save, organize and present various views of the model.

Scenes can control:
• Camera Location
• Hidden Geometry
• Visible Layers
• Active Section Planes
• Style and Fog
• Shadow Settings
• Axes Location

Which of these properties any one Scene retains is up to you via the Scene Manager.

Basically if you think on a “group” as an equivalent to another CAD’s Layer you won’t go too far wrong. You can name them and use the Outliner window to manage them and see where you are in the geometry.
Layers in SU work like viewing options - place all the groups you might want to hide onto a layer and click the switch. The on/off status of the layers can also be saved as a scene to revert to whenever you want.

So are the walls considered a component, I thought they were a group. Can you give me an example of a component when modeling a house.

Thanks

Anything can be a group or component.
A Component is just a Group with some extra abilities.
Copy a group and you have two unique objects, but copy a component and you have two linked objects. Edit one and the edits are reflected in the other.
So, basically, if you only want one of something it need not be a component, but if you will have many of the same it should be a component.
Simple example, the slab for the garage floor could be just a group, but the timber floor joists should be multiples of the one component.
There are other benefits to components, but that is a fundamental.
Personally I use components for nearly everything, I only group for temp things.

Components and Groups are different but very closely related in SketchUp (in fact, they share a lot of their implementation). So it’s a question of how you created each assembly, not just how they are “considered”.

The core difference is that a copy of a Group automatically becomes independent of other copies if you edit any aspect of it, whereas all instances of a Component share their geometry unless you make one unique - edit one and they all change together. Some people prefer Groups based on their workflow, whereas others use Components exclusively.

So, for example, you draw a wall and want to make it into a “thing” to keep it from sticking to and intersecting with other things. You select the edges and faces of the wall and then choose either Edit->Make Component or Edit->Make Group (or their keyboard or context menu equivalents). The selection then becomes a new Component or Group.

SketchUp layers do not own entities collections. They are basically a property / behavior sheet that you can share with multiple objects.

You do this by assigning various objects to use a specific layer (which uses it’s various properties and behaviors.)

Dave (and George) went on to say it correctly,…

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In many ways I think the SketchUp layer vs CAD layer debate is off base and gets way overblown.
The root of user’s confusion is not their misunderstanding Layer functionality in SketchUp.

Essentially, SU layers serve the same function as CAD layers.
The only exception being SU requires raw geometry always remain on Default Layer0

• Layers in SU control visibility and do not isolate geometry from interaction.
• Layers in CAD control visibility and do not isolate geometry from interaction.

What trips users is the fundamental difference in behavior of SketchUp geometry vs. CAD geometry.

Whether visible or not, by nature SU’s sticky geometry always interacts.
Unlike CAD, SU edges automatically break when they cross and inexorably stick together if they touch.
That is, unless the user deliberately tells geometry not to interact by grouping.

SU warns the user when invisible geometry interacts with visible geometry.

But by nature, CAD geometry behaves in opposing fashion.
Visible or not, crossing or merely touching, CAD geometry simply does not interact.
That is, unless the user deliberately tells it to interact.

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yea, probably wrong terminology - more accurate to state “if you want SU geometry to behave like CAD geometry then use groups rather than layers.”

I appreciate all of the help, when I am modeling the roof and am using the follow me tool, I cannot select a single line or plane since the walls are grouped and the follow me tool does not function properly.

Learning the basics are crucial to understanding the software. Spend time watching and reading tutorials, then ask questions.
Without the basics it’s like asking 'i have peeled a banana, why doesn’t my orange work the same way?

I’ve been watching numerous videos and enrolled to sketchup school, however finding it difficult since I have been using a CAD program since 1984.

Tip: This is my work-flow for creating roofs with the follow me tool:

  • Select the edges running around the top of the wall that you want the roof to follow and group them (not faces, just edges: this will in effect create a copy of the lines within a group).
  • While the group is still selected, move it up above the building a set amount (it’s annoying to try and select this group later because it lies on top of other lines and clicking will always select the line rather than the group)
  • Now edit this group and create the sectional profile to run round the perimeter. (I have some components already set up at different pitches)
  • Select all and then double click on the profile to de-select it and it’s bounding lines.
  • Select the follow me tool and click on the profile (if this didn’t work, you have probably missed an edge or you are trying to do two roofs in one action)
  • Come out of the group and move the roof back down to meet the walls.

Think of Groups and Components as containers which isolate SU’s perpetually interactive raw geometry.
Making logical sets of geometry into Groups and Components (aka ‘grouping’) is essential model organization.

In the real world we build a house out of wall systems, floor systems, roof systems, windows, doors and so on. They’re separate yet interdependent entities. One might approach modeling in the same way.

Either container entity serves to isolate/protect the raw geometry within its context.
However, Groups and Components have substantially different functionality when editing their geometry.

Certainly, one can build a model without grouping, but as model complexity increases, the ability to edit a single mass of interconnected geometry declines in quantum leaps.

This video describes the hows and whys of grouping geometry:


As for controlling visibility while building a model, there is another way besides fiddling with layers.
That is, the ability to seamlessly toggle model visibility while editing a Group or Component.

@Geo, I think you are mostly right but overlooking those users who may come to SketchUp from 2D drawing apps or may have come into CAD from such a background.

Those 2D apps have a very different conceptual basis than SketchUp or CAD. They literally envision a stack of distinct sheets (aka layers) spanning the third dimension, like a stack of printed construction documents. Layers “on top of” other Layers get a chance to modify what is seen in the view, for example by obscuring portions of what is “below”. But the contents of each layer are otherwise completely independent. Drawn items are indeed “on” a particular layer. Unless you redraw them on another layer, they don’t exist there! The interactions affect the view, not the contents, and are dynamic based on which layers are visible as well as the order they are stacked.

Unfortunately, the term “layers” was carried forward into 3D modeling where it cannot really describe the same concept. In 3D the third dimension is inherent to the model. The user can orbit to view from any direction, so there is no fixed notion of “in front” or “on top”. Stacking order is meaningless.

I suppose this term was chosen because 2D modelers’ clients were accustomed to saying things such as “show me how the HVAC layer interacts with the walls layer”, meaning “make visible where there are clearance or access issues etc. by showing the contents of these two layers on the same view”. But that had no bearing on whether HVAC actually modified the walls; it did not.

In CAD, as you observe, the conceptual shift was not really a problem because nothing interacts geometrically unless you tell it to. Practitioners and their clients were free to keep their notion of what “Layers” do even while not really understanding that the lack of interaction is not related to the visibility of the layers, or that you don’t view one layer through another in the same sense as in 2D. Said another way, funky interactions didn’t happen because they never happen, not because being on different layers prevented them.

In SketchUp, though, the interaction logic is reversed. Everything interacts unless you tell it not to by making a Group or Component. Visibility has no effect on interaction. That conceptual reversal is what messes up newbies in adapting to SketchUp’s use of the word “Layer”. They can no longer abuse the idea that something is “on” a layer. In addition, you can create really confusing issues by doing things such as associating the edges of a face with a different layer than that used by the face.

Particularly since Layout uses “Layer” in pretty much the traditional 2D sense, I think it was very unfortunate that SketchUp chose this term. It doesn’t clarify anything about what layers are for and opens the door for misinterpretation.

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In learning SU, I found the more one thinks of SU’s model space in real world terms, the easier it is to understand.

Again…
Think of Groups and Components as containers.
The ‘container’ isolates the raw geometry within, thus preventing interaction with geometry outside the container and so protecting the contents from inadvertent alteration.

In simple real world terms, a Group or Component is a bunch of stuff in a box.

The stuff inside the box cannot interact with things outside the box.
If one moves the box, invariably all the stuff inside the box moves too.
And if one wants to work with the stuff inside the box, they need to open the box first.

You’ll come across the term ‘context’ quite often here.
Entering or ‘opening’ a Group or Component for editing is simply opening the box to work within its context.

The topmost context is SU’s model space … the ‘box’ that holds everything in the model.
The modeling context within a Group or Component is separate and isolated from the rest of the model.

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