Tuesday, October 23, 2007

How Hidden Line Cache affects AutoCAD MEP Performance

Hidden Line Cache
The Hidden Line Cache is a feature that was implemented in order to improve the loading performance of drawings that contain ABS Objects, with the Hidden Line feature turned ON. It’s usage, which is a drawing-specific setting, is controlled in the ABS Crossed Objects tab of the Options dialog.

Fig 5 – Hidden Line Cache Control

As described in the Hidden Line Routine section, the end result of the Hidden Line routine is the assignment of portions of ABS objects to a Hidden Display Component. This assignment is not actually stored on the object themselves, but rather in a separate section of data.

The Hidden Line Cache feature allows for this data to be saved into the drawing database itself. This means that the data will not need to be rebuilt the next time that drawing is opened, since it already exists in the drawing. Without this option checked, the Hidden Line data will re-built each time the drawing is loaded, and exist only in the system RAM until the drawing is closed. The storage of the data in the Hidden Lines Cache will increase the overall size of the drawing file, sometimes significantly depending on the Hidden Line data generated by the routine. The tradeoff is that the drawing will load significantly faster with the Cache in place at time of load.

Hidden Lines and Xrefs

The existence of loaded xrefs that contain ABS objects, which are set to display Hidden Lines, in a host drawing will have a significant impact on the behavior of Hidden Line data for the host drawing. Since the xrefs contain ABS objects that will be factored into the Hidden Line routine, the program cannot know if those objects have changed significantly since the last time the host drawing was opened. Such a change would result in any data saved in the host drawing’s Hidden Line Cache not to be in sync.

Because of this potential for incorrect Hidden Line data of xrefed ABS objects, the data is never saved in the host drawing’s Hidden Line Cache, regardless of the setting highlighted in figure 5. This means that the Hidden Line data will be to be re-built EVERY time that the host drawing is loaded. This process can take a significant amount of time to complete, depending on the complexity of the layout.

This is why there may be a significant difference in load time between simply opening the xref directly and opening a host drawing that contains that xref.

Hidden Lines and Viewports on Layouts

In a given layout, each viewport has its own active Display Configuration setting. You change this by double-clicking in the viewport and making it active, and then changing the active Display Configuration. This allows for different viewports to display the same objects in a different way. An example of this would be a 1-Line and 2-Line display, as seen below.

Fig 6 – Different Display in Viewports

In some circumstances, a new Viewport is created with an active Display Configuration that uses Hidden Lines. Be aware of this setting, and make sure to use a Display Configuration that does not utilize Hidden Lines if the feature is not needed.

Mitigating Performance Impact of Hidden Lines

With a better understanding of the Hidden Line feature and how to control it, one can better make decisions regarding its impact on performance. The following items may be helpful in mitigating the performance impact of the Hidden Line feature.

  • First and foremost, have a Display Configuration that does not use the feature, and use this when display of Hidden Lines are not needed. Using such a “non-hidden line” Display Configuration will result in a significant improvement in load performance of a drawing, especially when there are xrefs containing ABS objects that use Hidden Line feature to display. Additionally, the existence of the Hidden Line data in the system RAM can have a significant impact on overall program performance. When new ABS objects are placed in the drawing, or existing ABS objects are moved, the Hidden Line data may need to be updated. This can add additional time to commands, potentially reducing productivity.

  • On a Paper Space layout, be sure to set the active Display Configuration for a viewport to a “hidden lines” Display Configuration only if such display is needed. If there is only text or non-ABS objects in the viewport, make sure to set active a “non-hidden lines” Display Configuration. This can make a significant impact on the time it takes to display the Layout.

  • If only using Hidden Lines for coordination, consider turning off Hidden Line gaps. This additional calculation in the Hidden Line routine contributes to the overall calculation time, and adds additional size to the Hidden Line data stored in system RAM.

  • Because of the impact of xrefs in a host drawing, as discussed in the Hidden Line and Xrefs section of this document, consider how you plan to structure your project drawings, and what xref relationships will be created as a result.

  • Unless there are specific reasons to reduce the physical size of drawings, consider using the Hidden Line Cache feature when possible. This will help to improve drawing load performance in situations when the Cache is utilized.

  • Flex Duct objects contain annotation lines that give them the “flex” appearance. The style of these annotation lines can be controlled by the user. Some of these styles use extensive linework to give the desired look for Flex Ducts. These annotation lines are included in the Hidden Line Routine, and can add significant complexity to the calculation. Unless you require that Flex Ducts be shown with Hidden Lines, consider using the 2 Line Display Representation to display these objects in your drawings. This can reduce the complexity of the Hidden Lines Routine, thus improving load time and reducing the overall size of the Hidden Line data stored in the system RAM.

Monday, October 22, 2007

Hidden Lines: Explained By Autodesk's Kyle Bernhardt

With the release of ABS 2007, what were previously called Haloed Lines have been globally renamed to Hidden Lines globally across the product. For those running a version below ABS 2006, replacereferences to Hidden Lines with Haloed Lines.

Hidden Line Routine
The Hidden Line routine determines what portions of ABS objects will need to have the Hidden appearance, due to other ABS objects being located above them. These portions of the ABS object deemed to be “hidden” are then assigned to the “hidden” Display Components. This allows for complete control of the Hidden Line Layer, Color, Linetype, Lineweight, and LT Scale in the program.

Fig 1 – Hidden Display Components

These settings are typically defined by the Layer assigned to the Hidden Display Components. The remaining Hidden Display Component properties are set to BYLAYER, which maps them to the Layer’s properties. Assigning the same Layer to the Hidden Display Components of all ABS objects allows for one layer to control the display of Hidden Lines throughout an entire drawing. In this scenario, modification of something like the Color of the Hidden Line Layer will propagate to all Hidden Lines.

Control of Hidden Line Display
The item that controls whether Hidden Lines are used for a particular ABS object type is the Display Representation (DR) that’s used to display that object in the current viewport. The Display Representation that’s used is controlled by the current Display Configuration. See the diagram below for illustration of this fact.

Fig 2 – Display Representation Assignment

For ABS Objects, the Plan Display Representation utilizes the Hidden Line feature. In previous versions the HaloedLine Display Representation utilized the Hidden Lines feature.

If you wanted to create a Display Configuration that does not utilize the Hidden Lines feature, you would associate that Display Configuration with a Display Set which does not assign the Plan Display Representation to ABS objects. You will most likely use the 2 Line Display Representation instead, which displays objects in the same way as the Plan Display Representation, without Hidden Lines. The MEP Basic 2-Line DC, which is contained in the default ABS template, is a good example of such a Display Configuration.

Hidden Line Gaps
The Hidden Line routine also has the ability to apply a gap in the display of an ABS object when the routine detects that a portion of that object is hidden by an object above. See the figure below to illustrate this feature.

Fig 3 – Hidden Line Gaps

This feature produces a visual effect that complies with some existing drafting standards, and is a desired effect for the production of Construction Documents.

This is a drawing-specific setting, and is controlled in the ABS Crossed Objects tab of the Options dialog, see below.

Fig 4 – Hidden Line Gap Settings

Enabling this feature will result in an additional calculation added to the Hidden Line Routine.

Building Product Search Module Now Available to AutoCAD Architecture Subscription Holders

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The Building Product Search module allows users to integrate product selection and specification writing within AutoCAD Architecture software. It provides rapid electronic access to more than 1,250 building product catalogs from hundreds of manufacturers. As products are selected, up-to-date specifications are automatically created, consolidating a multi-step process into a single step. Customers can find tutorials on how to use the module within the product.

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Monday, October 01, 2007

How to Successfully Implement AutoCAD MEP

A White Paper from Autodesk

This paper discusses the implementation and deployment of MEP (mechanical, electrical, plumbing, and fire protection). Most organizations do not have a comprehensive or effective approach to applying new technology to existing processes. This paper explores the considerations necessary to make informed decisions, and presents strategic approaches to achieving the most effective implementation of AutoCAD MEP for your organization.

Changing the Process

An increasing number of engineers are making the switch from the traditional 2D drafting software to 3D object-based design software. However, with this switch comes the realization that existing processes themselves must be examined, adjusted, and refined, or perhaps, fundamentally redesigned in order to realize continuing gains in effectiveness and stay competitive in the industry. The challenge for most organizations in doing so is that day-to-day productivity must be maintained on projects in progress, affording little opportunity for the fundamental consideration of such process issues and no margin for error.

In order to successfully implement any new technology, one must begin by identifying and defining the underlying processes necessary to produce their designs. Do your engineers work on projects in teams, or do they work individually? Do you have CAD standards that must be adhered to? How proficient are your engineers today in the use of your current technologies? Besides these common issues, you will have many unique to your organization that must also be identified early on.

Object CAD Technology

Object CAD technology has changed the way industry professionals think about how technology can be applied to engineering design. Instead of working with traditional lines, arcs, and circles, you work with 3D geometry, or “objects”, like equipment, ducts, and pipes that are representations of real-world objects. The objects know how to interact with other objects. For instance, a 12-inch duct knows that only 12-inch duct components can connect to it. By working with objects you create a complete model of your design and then through the use of automated tools generate conventional 2D construction documents. And because the model carries rich data about the design in the objects, design data can easily be extracted from the model to carry information downstream in the design process.

Improving the Process

Engineers who are reluctant to switch to an object CAD technology should ask themselves what their objective is – to make a drawing or to produce a design that can be effectively communicated for construction. Although the choice to make the switch may make sense and seem fundamental, all too often the barriers of implementation and deployment overwhelm organizations resulting in the continued use of outdated or inefficient technologies. With a clear understanding of existing processes, and an equal understanding of the capabilities of AutoCAD MEP and how they can be applied to your processes, planning a successful implementation can become clear and less daunting.

All design and construction projects follow a general process that proceeds through certain phases from inception to completion, with minor variations depending on the requirements of the project. The phases in the process that are most common to engineering design and construction projects are:

• Preliminary Design

• Design Development

• Construction Documents

To improve the process using AutoCAD MEP, you need to look at each phase and determine specifically how this new technology can benefit your organization.

Improvements in the Preliminary Design Phase

Using traditional methods, developing preliminary design documents can be a very manual process; conceptualizing system designs from preliminary sketches, defining general size and area requirements by approximating the architecture of the building, identifying design criteria through time-consuming analyses and detailed calculations.

With AutoCAD MEP you can reduce manual tasks throughout the preliminary design phase by producing a preliminary model of the spaces intended to be serviced. Through the massing of building elements like spaces, doors, and windows in an object-based CAD environment, much of the conceptual information required can be automatically generated for you. Benefit from calculated values for space dimensions, square footages and volumes, and estimated loads and quantities. Take advantage of the design data automatically generated to determine design criteria.

Improvements in the Design Development Phase

During the development of a building project, changes can cost time and money and negatively affect the project from staying on schedule and within budget. Traditional methods typically do not facilitate change effectively. The creation of design documents can be laborious and require a vast amount of low-value drafting tasks including manual checking of work.

AutoCAD MEP allows a project team to make changes to the project at any time during the design process more quickly and effectively. With design data readily accessible in the model, critical design information is immediately available so that project-related decisions can be made efficiently. This gives the project team more time to focus on the actual design itself.

In addition, AutoCAD MEP streamlines processes, such as part selection and system sizing, by offering intuitive tools that assist you in developing an accurate design. Parts can be selected directly from catalogs that provide an extensive collection of industry-standard parts. Systems can be sized based on the design data embedded in the model that was captured at the point of creation. This allows the project team to deliver better work faster, because it means that their design requires less time and effort.

Improvements in the Construction Documents Phase

The intent of a building systems design project is to create a building that will run efficiently. Using traditional methods, coordination between all the different disciplines is usually the biggest problem. When ever a change is made to the design capturing that change throughout the construction documents many times does not happen because of the time and effort required. The result is lack of coordination that ultimately can have significant impacts on the construction of the project.

AutoCAD MEP helps to ensure design coordination by allowing you to take advantage of the design data captured in the model. With the use of automated tools, you can quickly produce many views of your model including sections, elevations and 3D representations, and gain feedback about your design by generating schedules and detecting spatial interferences. Whenever a change is made to the design, all the consequences of that change are automatically coordinated throughout the project ensuring that the change is reflected in all of your construction documents. The automated design coordination provided by AutoCAD MEP helps to eliminate coordination mistakes and improve the overall quality of your work.


Once you have determined that AutoCAD MEP is a viable solution based on the benefits your organization can gain from process improvements, you must take a realistic look at the situation in your organization. The key to any successful software implementation is assessment. Many organizations are in the habit of looking at new technology to make their jobs easier and remain competitive. However, all too often the decision to adopt a new technology is made with the wrong expectations. In order to eliminate unrealistic expectations, maximize the value of your investment, and minimize implementation risks, it is imperative that you take a closer look at the more tangible issues surrounding implementing Autodesk Building Systems:

• Hardware Requirements

• Optimization and Configuration

• Installation and Deployment

• Training

• Support

Optimization and Configuration

Out of the box AutoCAD MEP is set up for designing systems based on common industry standards. You can get up and running quickly using basic model and sheet templates that include generic layout tabs and borders; lay out systems based on AIA layer standards using predefined layer keys for layer assignment, color, linetype, and line weight, work with default part catalogs to generate designs based on common off-the-shelf parts, and use standard profiles to set up your workspace with general menus, tool palettes and tool bars.

Even though AutoCAD MEP provides generalized configuration out of the box, additional set up is almost always necessary. Most organizations have CAD standards that must be adhered to, work on projects that require unique parts or equipment, and have established practices that demand custom workspaces and default settings. For an implementation of AutoCAD MEP to be successful it is crucial that day-to-day production is maintained. Through optimization and configuration you can provide users with a level of familiarity that helps to ease the transition to a new technology.

Installation and Deployment

Installation and deployment of a new technology depends heavily on your organizational structure. Determine how many users will be affected. What kind of time constraints do you have? What directory structure will be used? Are components being loaded locally or on a network? Your goal here is to leave nothing to chance. Failure to do so may result in production slow downs, or worse, broken systems.

Determine the actual deployment process. Each step in the process should be looked at in detail, documented and tested. This will help to ensure that each deployment will be done identically.

Create a contingency plan if your implementation schedule is interrupted like staggering deployments to individuals or groups, or leveraging nights and weekends for the actual installations to minimize down time.


Training requirements significantly increase the implementation time and cost. First and fore most, you will need a training budget. In order to establish a training budget you need to ask yourself two important questions:

1. How will AutoCAD MEP be used in your organization?

2. What is the proficiency level of your users?

The answers to these questions will help you determine the type of training needed as well as how MUCH training will be required. When it comes to CAD software, one can never have enough training. Remember that AutoCAD MEP presents a change in process when implemented successfully. Therefore, training requirements must be accurately identify in order to reap the full benefits of implementing this new technology. Process changes take time; established practices must change and old habits must be broken. Be realistic about training requirements and take them into consideration when planning the implementation. Look for ways to ease the transition. Provide training during or shortly after deployment to allow users to apply what they learned in training right away.


Even after installation, deployment, and training takes place, the implementation process is not complete. Technical support must be available and easy to access for everyone. Don’t expect CAD users to attend training and return to the office knowing everything to make AutoCAD MEP purr on their desk. There is always a learning curve for new technology and by taking the steps necessary to provide adequate technical support, users will have the help they need back on the job.

Every organization will have different ideas of how to provide ongoing technical support. Remember it is not necessarily the method of support but that support is available.

Pilot Project

Consider a pilot project. Most organizations that are talking about investing thousands of dollars in new technology want proof-of-concept. Set up a few users in a small-scale production environment to evaluate your implementation plan and to validate the results of your assessment. This will be a good indication if you identified the critical issues to be considered in your organization, accurately estimated time and costs, and set realistic goals that can successfully be attained.


Implementing a new technology, specifically AutoCAD MEP, may be frustrating at times; however when all is said and done your organization can reap tremendous rewards from a successful implementation. If you have considered each of the issues previously discussed and objectively weighed the strategic approaches presented, you will have addressed the critical steps in achieving the most effective implementation of AutoCAD MEP for your organization. Taking the time to strategize and plan for an implementation of AutoCAD MEP will minimize the time and efforts required for a successful implementation and maximize your return on investment.