Littleme,
Reid gave a great explanation of PN. I would like to add this.
It has nothing to do with layers, you are creating a drawing and a View
is also a drawing file. Let's put Project Navigator (PN) aside for the
moment. An xref is a drawing file (.dwg) that is referenced by another
drawing file without having all the objects inside both files. So the
Architect can draw his walls of the building in one file, place the
ceiling grid and structural in another. The engineer draws duct and/or
pipe in his .dwg file or files, electrical in their own .dwgs. Then, as
needed, they can xref them together. The Xref word can be used as both a
noun and a verb. To link the files together is to xref (verb) the files
together; the file that was brought in to the other file is called an
xref file (noun).
Xreffing is a way of breaking up the files so that:
1. it's organized
2. file size is smaller
3. other disciplines can xref in, only those files containing objects
they want to see in their file. Hence the organization mentioned in 1 above.
4. breaking the model up into phases or status like "Items to be
demolished, existing items, proposed items, Phase 1, 2..."
5. keeping text separate from the model
6. more than one person working on model/sheet at a time
Before PN, the Architects would make their background in one or across a
few model dwg files. The mechanical engineer xref'd those background
file into his file, and begins to make his model drawing the duct,
diffusers, etc.
Someone would make a new dwg file containing the titleblock with all
common elements and create a block for titleblock elements that changed
on each drawing.
Each discipline would create a new dwg for their sheets, xref in the
various background files, xref in the common titleblock file and then
insert the sheet specific block while tweaking the block text to the sheet.
So each discipline had one or two model files, and a sheet file.
This allowed more than one person to work on a portion of the model or
sheet at a time.
There was arguments about where text should go...in the sheet or in the
model. If in the model, then other disciplines saw the text when xref'd
into their files and would continuously be turning on/off
layers...that's a lot of work and coordination by each discipline. This
was worsened, when disciplines needed enlarged scale plans with the same
text at different scales. People drew the text multiple times on
multiple layers.
Architects mostly, but other disciplines too, have needs to make
elevations, details and play with different scenarios which go on
various layers turned on or off. We've all seen portions of the floor
plan drawn off to the side...it's very annoying when you xref in a
background and zoom to extents...to find the extents are way out there,
the background is real small, all because of one or more objects drawn
out in left field.
Last issue, file sizes are getting bigger and hence the need to break
objects out into more xrefs. But there is a labor cost, more files, more
coordination and setup.
We created project navigator and fields.
Constructs are where each discipline place their model objects...they
can break the model into as many files as needed to be organized and
keep file size down. File size smaller, faster computer. The Construct
files (and others) are tracked by PN. It creates an xml file. Each
Construct is assigned a Level, Division, Discipline...and it remembers
file locations, folders and provides a means to coordinate Fields.
Elements are also xref drawing files, but PN knows that the geometry
placed in these files span between levels and divisions...or are
repeated many times. For example, all first floor walls go on a
Construct, and the stairwell that bridges between first and second
floors goes in an Element. If you are making an apartment building and
all bathrooms are the same, make it in an Element file. Then you can
xref that element file into a Construct, multiple times over in many
different locations and rotations. PN will track each instance and allow
walls to properly clean up (I'm not an architect, but this is my
understanding, so don't hold me to this). Constructs are for creating a
model or portion quickly and in ABS we set our Constructs to a Display
that allows us to see all of the model needed to quickly create our objects.
Views are somewhat optional. The model files xref into a View drawing
and then text and other annotations are drawn. This keeps the model,
which is used by other disciplines, separate from the anno that other
disciplines do not want. A user can several View files, xref in a model
into each and then set the anno scale differently in each. This keeps
the layers down and coordination to a minimum. The Architects and other
disciplines can make non-model Views like details, riser diagrams,
schedules, etc in dedicated View files thus keeping the model Construct
files clean and file size down for other disciplines. When a detail is
created in a View, the Fields are in the Construct??? to coordinate
callouts, keeping them in synch with the detail number. The View Display
setting can be changed from the Display in the Construct to be ready to
be plotted. Construct is for quickly/cleanly creating models, View
drawing is quickly created to go on a sheet somewhere.
Sheet drawings pull it all together and are plotted. Views are
drag-n-dropped off PN onto a Sheet. It's quick and this simple action
brings in all the model constructs needed to make the View. Users can
bypass the whole View and manually bring in a Construct...just like they
did before PN...but they miss out on a lot of benefits that come with
Views. It's worth it on a small project. Sheet files are smaller because
the model is xref's, the anno is xref'd and often the titleblock is
xref'd. What's left is sheet specific block, sheet specific notes or key
notes, revision clouds maybe, time/date stamp. This makes plotting
quicker too.
PN coordinates and organizes all the various xrefs. It provides a means
to quickly xref all the files together saving a ton of time. It keeps
track of Fields, anno scale in Views and wall cleanup in Elements.
People are beginning to realize this, but PN has the capability to
create a whole Project Template(s)...storing the Display, scale and xref
dependencies for every Construct, Element, View & Sheet for every
discipline. It takes a lot of upfront planning and setup to create one,
but think of all the time it saves creating the entire project with the
click of a button. Of course no template covers all bases, there will
always be some setup time, tweaking stories or levels, Fields, tailoring
it to the project, but it is a good start and time saver.
PN does have it's limitations, defects, etc, Autodesk is aware of them
and we are working on improving it continuously. It'll only get better
thru the years.
I know this post was lengthy, but hopefully I've filled in some of the gaps.
Joshua Benoist, PE (Autodesk)
Reid M. Addis wrote:
Project Navigator has 4 dwg file types: Elements, Contructs, Views, and
Sheets. They work something like the following:
Project Navigator is designed so that Element files are externally
referenced into Construct files. Constructs in turn are externally
referenced into View files, which then are externally referenced into Sheet
files.
A Construct is a Level and Division specific portion of your building that
will be used in multiple View files. The building objects in these files
exist in one and only one point in space. For example, walls for the second
floor that exist there and nowhere else would go in a Second Floor Construct
file, which in turn is associated with the Second Floor Level of your
project. This file will later be externally referenced (xrefed) into several
View files such as a Dimensioned Floor Plan; a Reflected Ceiling Plan; a
Furniture Plan; etc. Objects that exist in a unique Level and Division in
your Project but are not used in multiple View files will be placed directly
in those View files, such as furniture.
An Element file contains objects that will be used in more than one
Construct, View, or Sheet file that do not exist in a unique spatial
location. Examples of this might be a typical building column grid, a
bathroom-elevator core, or a titleblock. Unlike Constructs that are
associated with Levels when they are created, Elements are not associated
with specific Levels in your Project.
Okay, let's review Reid's Rules for Project Navigator so far.
1. If drawing entities exist in a specific point in space AND will be
used in more than one View file, create them as Constructs (the walls, doors
and windows will be used in the Dimensioned Floor Plan, Furniture Plan,
Finish Plan, Reflected Ceiling Plan, etc. View files so they are
Constructs).
2. If drawing entities will be used in more than one View file
but DO NOT exist in a specific point in
space, create them as Elements (buildings cores, column
grids, and title blocks are excellent candidates for
Element files).
Here you are in the early stages of your Construction Document (or Design
Development) phase of your project. You know you want to plot the plans at
¼"=1'-0" scale. You know you want ½" scale plans of the stair and core
area. You know you want ¼" scale Elevations and Sections of the building.
You may even know which rooms you want ½" scale Interior Elevations of.
So, at this point, you know what you want to plot. The problem is you don't
yet know where you want to plot them. Here are three more of Reid's Rules
for Project Navigator
1. What you want to plot goes into View files.
2. If what you want to plot exists in a specific point in space, such as
the 2nd floor furniture, but IS NOT USED in more than one file, put it in a
View file.
3. Where you plot from is your Sheet file.
Here are the basic steps once again:
1. Set up the Project in Project Browser
2. In the Project tab, create your Levels and Divisions
3. Create your Construct and Element files in the Constructs tab.
Remember, you drag and drop Elements and/or Constructs into Construct files.
Element files are also dropped into Sheet files.
4. Create View files by specifying the associated Level and Division. In
many cases, you may not specify any level, such as Detail files.
5. Add ALL of your Annotation to the View files. View files are where
you create What you want to Plot. Create Named Model Space Views to the
appropriate scale in these files.
6. In the Sheets tab, create your Sheet files. Sheet files are
Where you Plot your Named Model Space Views
from the View files. Simply drag and drop Named Views onto
Layout tabs. Add Title Marks, dragging and \ dropping
them back onto the Views created under the Sheet names in Project Navigator.
Does that help?
