Visual Fidelity for Annotative Objects in Previous Releases

You can specify that annotative objects maintain visual fidelity when they are viewed in AutoCAD 2007 (and earlier releases) with the SAVEFIDELITY system variable.

If you work primarily in model space, it is recommended that you turn off visual fidelity (set SAVEFIDELITY to 0). However, if you need to exchange drawings with other users, and layout fidelity is most important, then visual fidelity should be turned on (SAVEFIDELITY set to 1).

Annotative objects may have multiple scale representations. When visual fidelity is on, annotative objects are decomposed and scale representations are saved (in an anonymous block) to separate layers. These layers are named based on their original layer and appended with a number. If you explode the block in AutoCAD 2007 (or earlier releases), and then open the drawing in AutoCAD 2008 (or later releases), each scale representation becomes a separate annotative object, each with one annotation scale. It is recommended that you do not edit or create objects on these layers when working with a drawing created in AutoCAD 2008 (and later releases) in AutoCAD 2007 (and earlier releases).

When visual fidelity for annotative objects is not selected, a single model space representation is displayed on the Model tab. Depending on the setting of the ANNOALLVISIBLE system variable, more annotation objects may be displayed on the Model tab, and more objects may be displayed in paper space viewports at different sizes than in AutoCAD 2008 and later releases.

For a procedure to set visual fidelity for annotative objects, see To save drawings with visual fidelity for annotative objects.

Annotative Object Properties in Previous Releases

In an AutoCAD 2008 drawing, when an annotative block does not have its paper orientation set to match the layout, and the block contains multiline attributes that are based on a text style that is not set to match the orientation of the layout, the attributes may shift positions if you pen this drawing in AutoCAD 2007 (and earlier releases).

Layer Property Overrides in Previous Releases

When you open an AutoCAD 2008 drawing containing layer property overrides, overrides are not visible. The property override settings are retained when the drawing is saved in a previous release, and are visible again when the drawing is opened in AutoCAD 2008.

If a viewport containing layer property overrides is deleted when the drawing is opened in a previous release, the override settings are not retained and are not available when the drawing is opened in AutoCAD 2008.

When the VISRETAIN system variable is set to 0 when the drawing is opened in a previous release, xref layers containing viewport property overrides are not retained.

If you open an AutoCAD 2008 drawing in a previous release, property overrides may display in a thumbnail image. When the drawing is saved with a layout tab, and then opened in the previous release, those property overrides do not display.

DGN Underlays in Previous Releases

DGN underlays do not display in releases prior to AutoCAD 2008.

Dimension Enhancements in Previous Releases

AutoCAD 2008 dimension enhancements are lost when they are edited in earlier releases. If you don’t change these dimensions, they are restored when you open the drawing in AutoCAD 2008.

The following dimension enhancements do not lose visual fidelity in previous releases if they are not edited:

• Dimension breaks
• Jogged linear dimensions
• Inspection dimensions
• Angular dimensions that are dimensioned using the quadrant option
• Arc extension lines for radial and diameter dimensions

Multileader Objects in Previous Releases

Multileaders display as proxy objects in releases prior to AutoCAD 2008. The PROXYSHOWsystem variable controls the display of proxy objects in a drawing.

MTEXT Paragraph and Paragraph Line Spacing in Previous Releases

Some of the new paragraph spacing and paragraph line spacing options are not supported when an AutoCAD 2008 mtext object is opened in AutoCAD 2007 (and earlier releases).

The following mtext formatting features have no visual fidelity in previous releases:

• Paragraphs with justified alignment
• Paragraphs with distributed alignment
• Fields that wrap across columns
• Fields that wrap across lines that have new paragraph alignments
• Paragraphs with non-default alignments in mtext without left object-level justification

The following mtext formatting features have some visual fidelity in previous releases (when it’s possible to add white spaces or replace text with white spaces):

• Paragraphs with non-default alignments (other than justified or distributed) in mtext that has left object-level justification
• Paragraphs with tabs using new tab alignments (center, right, or decimal alignment applied)
• Paragraphs with new line spacing that can be "approximated" with "tall" spaces

Mtext with new formatting that is edited and saved in previous releases loses the new formatting when re-opened in AutoCAD 2008.

Tables in Previous Releases

Editing AutoCAD 2008 tables in previous releases removes AutoCAD 2008 table formatting. Also, AutoCAD 2008 table cells with long block and text strings may extend outside of cell borders when opened in previous releases.

Data Extraction Tables in Previous Releases

For tables that were created with the Data Extraction wizard in AutoCAD 2008, you can’t edit or update the extracted data in previous releases.

Materials in Previous Releases

AutoCAD 2008 introduces new procedural maps for materials and luminance. Drawings created earlier than AutoCAD 2007 that contain materials need to be converted. AutoCAD 2008 provides a system variable, 3DCONVERSIONMODE, that is set to automatically convert old materials to the AutoCAD 2008 format. However, there are some fidelity issues when saving back to previous versions of AutoCAD.

• Procedural maps Checker, Noise, Speckle, Tiles, and Waves are not available in AutoCAD 2007 (and previous releases.) They do not appear when an AutoCAD 2008 drawing is opened in AutoCAD 2007. Marble and Wood are available but the material mayshow some variation.
• The behavior of the Opacity map channel under the Realistic material type has been corrected in AutoCAD 2008. In AutoCAD 2008, the Opacity map channel behaves like a transparency map, where white is transparent and black is opaque (this was how it behaved prior to AutoCAD 2007). In AutoCAD 2007, white represented opaque areas and black represented transparent areas.
• The spherical map rotation is different in AutoCAD 2008. When you open a drawing prior to AutoCAD 2008, the seam for the map is towards the +Y axis. In AutoCAD 2008, it is towards the +X axis.

Lighting in Previous Releases

AutoCAD 2008 provides two options for lighting: standard (generic) lighting and photometric lighting. Previous versions offered only standard (generic) lighting. There is no explicit conversion required for lights from AutoCAD 2007 to AutoCAD 2008. Drawings from AutoCAD 2007 open by default in AutoCAD 2008 in the standard (generic) lighting workflow. The additional photometric properties available in AutoCAD 2008 are available as soon as the photometric lighting workflow is enabled in the drawing.

There is a conversion process required for drawings with lighting prior to AutoCAD 2007. You can use a system variable, 3DVCONVERSTIONMODE, to automatically convert drawings with lighting from previous versions to the AutoCAD 2007 and AutoCAD 2008 lighting format. 3DCONVERSIONMODE has three settings. If set to 0, no conversion takes place. If set to 1, the default value, the conversion takes place automatically. If set to 2, then you are prompted when lights need to be converted and will have the option to convert or not to convert.

Other lighting fidelity issues include

• Lights in blocks. Lights in blocks created in AutoCAD 2008 do not always display in AutoCAD 2007.
• Texture illumination. In AutoCAD 2007 (and earlier releases), you can’t add lighting to textures. In AutoCAD 2008, you can.
• Ground Shadows. The intensity of ground shadows in AutoCAD 2008 depends on the brightness of the light and angle of incidence.