ADVERTISEMENT
LASN Technology Sept, 200409-01-04 | News



Quick Keys: Rendering an AutoCAD drawing in Photoshop

By Ashley Calabria






Figure 1. The sample AutoCAD drawing before transfer into Adobe Photoshop for adjustment.
img
 

Part 1 – Bringing an AutoCAD drawing into Photoshop

Is there any question that the learning curve for new computer skills is quite high? Even for those who have learned the basics, they barely have time to understand what is happening before some aspect of the system is changed. It can be overwhelming how fast programs are upgraded and new software is published.

The Quick Keys series is here to help. This is the first of three articles presenting computer skills that can help an individual or firm complete work in the most efficient way.

This lesson covers the steps in transferring an AutoCAD file to Adobe Photoshop?EUR??,,????'??+where color and layer changes can be made more easily. A common mistake is forgetting to keep file size low, resulting in bulky files that can bog down memory. Rendering in Photoshop helps keep files compact and offers options that can spur the designer?EUR??,,????'???s creativity.






Figure 2. The base drawing is now ready for Photoshop. Labels and other unnecessary information have been removed while still in AutoCAD. They will be replaced later.


Quick Keys lesson two will present rendering in Photoshop. Lesson three will cover returning the drawing to AutoCAD.

The series will make sense if you assume the following:

  • The drawing is already in AutoCAD with layers.
  • The drawing is in Paper Space and scaled, just like it would be if it was to be plotted.
  • Photoshop will be used for rendering.

The most important thing to remember is that Photoshop will read an AutoCAD drawing as a raster image and vice verse. A rendered Photoshop drawing, even though it was originally from AutoCAD, is read as an image, not a drawing with layers. This sample drawing is simple but will help familiarize the reader with the commands used for AutoCAD and Photoshop for rendering.

Preparing an AutoCAD drawing for Photoshop

In Paper Space, turn off all the layers that are not part of the base drawing that you want rendered. This would be the contours as well as any labels or information that you will not want to render. You can put them on later in Photoshop or when you bring the drawing back to AutoCAD. Figure 1 and 2.

Saving the drawing with the PDF extension

Go to File, then Plot and change the plotter configuration name to Acrobat Distiller. You can also select the PDF writer. If you use the PDF writer, select the Properties button and change the resolution to 150 dpi.

If using Acrobat Distiller, follow these steps.

  • Click on the Properties button.
  • Click on the Custom Properties button.
  • Click on the Adobe PDF Settings tab.
  • Change the general conversion setting to ebook.

This saves the drawing with 150 dpi, which will give a good quality color print as well as keep file size relatively low. If a higher quality print is needed, choose Press, which saves the drawing with 300 dpi. For drawings that will only be seen on a screen, choose Screen, which saves the drawing with 72 dpi.






The sample drawing is now ready for rendering in Part 2 of the Quick Keys series.


Click on OK to close the Acrobat Distiller Document Properties and OK to close the Plotter Configuration Editor. Select OK to create a temporary PC3 plotter configuration for this plot.

Back in the Plot dialog box in AutoCAD, make sure you have the plot style selected that you want as well as the paper size (this sample is 17” x 11”) and orientation. A full preview demonstrates how your drawing will save.

Select Plot. You will be asked where to save your drawing. Select your destination and then select Save. It will save with a PDF extension that allows you to open it in Photoshop.

The sample drawing is now ready to bring in to Photoshop.

Opening and preparing the drawing in Photoshop

This example uses Photoshop Elements. Start Photoshop and open the PDF file from where it was saved, then click Open.

In the Rasterize Generic PDF Format dialog box, make sure the drawing size matches the paper size you saved in AutoCAD and that the resolution matches the dpi. The sample drawing is 17” x 11” and was saved with 150 dpi (ebook), then OK.

When the drawing opens, it has a checkered background which makes the drawing difficult to see and work with. The checkered background in Photoshop stands for a transparent background. It is easier to use a white background.

Click on the Set Current Colors to Black and White from the tool bar.






The Adobe Photoshop Layers Palette. Eye icon at left turns layers on and off. Brush feature shows which layer is current.


Then go up to Layer, select New, then select Background From Layer.

The drawing should now be on a white sheet of paper so it is easier to see.

History Palette

There are two palettes that you should keep open. One is the History Palette. It allows you to go back if things are not looking good. It is like the undo in AutoCAD. To open it, go to Window, then find Show History.

It is a good idea to maximize the number of commands that the history palette remembers. Go to Edit, then Preferences, then General. Change the History States to 100. The History Palette is now able to remember up to 100 prior commands.

Layers Palette

The other palette that is necessary to have open is the Layers Palette. To open it, go to Window, then find Show Layers. The Layers Palette is different in Photoshop then it is AutoCAD. Take a look at the layers palette.

The arrow to the right of the Layers tab is called the Layers Palette Menu. Selecting it allows you to make new layers, delete layers, or merge layers. Don?EUR??,,????'???t worry about blending modes (the menu that reads Normal) for now. The opacity allows colors to show solid or transparent. This is useful for showing plant materials that are under a large tree for example. Turn down the opacity and it is possible to see through the rendered tree. Lock allows a layer to become locked so that alterations cannot be made to it. Each of the layers has an eye and a brush. The eye turns layers on and off (visible or invisible). The brush tells you which layer is current.

Double click on layer 1 and rename it BASE. This is the layer that needs to be current during selections.

The drawing is now ready for rendering in Part 2 of this series. Save this drawing with the Photoshop PSD format.


img