Why is my AutoCAD-saved pdf file showing furry solid-hatched logo?

[Dana W]

Dear Dana, thank you so much for your help!! So sorry I was too busy too reply in time. Your logo hatch looks much better than mine. Does it mean I need to change Spline to Polyline before I do hatch? How do I do that? Thank you very much!

The problem is not with the splines, really. It is the ragged nature of the curves, and the places where curves join the straight lines. The more tiny little spaces you make AutoCad force the hatch into, the more conflict there will be with resolution in the pdf image. The linework has to be as smooth as possible.

 

At any rate, you can change a spline to a polyline by selecting the spline, then execute the pedit (polyline edit) command. The program will ask you if you want to change it to a polyline. The default is yes, so just hit enter. You can also change multiple lines or splines. Execute pedit, hit the down arrow, and a "multiple" prompt will be shown. Select that, and then select a bunch of splines, then go from there.

 

There is a problem with changing splines to polylines however. You may be confronted with hundreds of polyline vertices (grips) where the splines only had a few.

 

The best way is to start with polylines from the beginning. You do know that once you start the polyline, you can type A for arc and it will draw an arc instead of a line. It will keep drawing arcs until you type L for line again.

[junehe]

Thanks a lot Dana! I guess I will have to redraw all the letters using polylines. One more question, If I want to use an existing font to make a logo, can I use the font from my pc font library directly? Do I have to use some AUTOCAD specific fonts (another format)? If yes, where do I get them for free? Thanks!!

[Dana W]

Thanks a lot Dana! I guess I will have to redraw all the letters using polylines. One more question, If I want to use an existing font to make a logo, can I use the font from my pc font library directly? Do I have to use some AUTOCAD specific fonts (another format)? If yes, where do I get them for free? Thanks!!

Generally TT fonts are not vector files, they are raster shapes, and they have no edges. There is no "direct" method to change them to geometric objects within AutoCad. I don't do CNC signage and logo's so I am not sure how to go about it without simply drawing the characters myself, which I have done once or twice. I don't have a lot of information on using AutoCad for large CNC lettering.

 

Two factors for clean output. Arcs and lines MUST join at tangent points, and don't enlarge a tiny modelspace logo object with the viewport scale. For instance, don't plot a one inch tall logo at, say 20:1 and expect it to look clean. If you want a 100 foot tall sign, draw the characters 100 feet tall.

[junehe]

Thanks Dana! This really helps!

[Dana W]

Thanks Dana! This really helps!

I may have been too hasty. I use AutoCad LT so I do not have Express tools available, and don't often remember their existence. I believe, in full AutoCad, If you installed express tools, you may be able to at least explode the text to their individual characters using a special explode command that only exists in express tools. I am not sure what other manipulations there may be in express tools. Something in there may help.

[lrm]

Actually, True Type fonts use B-Splines and are not raster based. B-splines were the original splines used in the old AutoCAD pline to spline feature. The newer AutoCAD splines are based on NURBS (non-uniform rational B-splines). B-splines forced 1st derivative continuity (no breaks in slope) throughout the spline and could not be randomly trimmed without changing the shape of the spline. This was part of the reason for going to NURBS. True Type fonts use B-Spline pieces to outline the shape of a letter. A prime advantage of True Type fonts over older fonts is the scalability.

 

Some of you old timers may remember the pre-True Type days and the need to purchase hardware cartridges for laser printers with a selection of fonts and different point sizes. The 18 year old HP Laserjet 4 on my desk, which still works fine, has a door for the cartridge. The original AutoCAD fonts were based on straight lines sketched on a crude 5x7 grid. The "A" of the txt.shx font was particularly distinctive and immediately said "this drawing was done with AutoCAD". The availability of True Type fonts in AutoCAD is relatively new.

 

 

Here's a link on True Type technology: http://www.prepressure.com/fonts/basics/truetype

[Dana W]

Actually, True Type fonts use B-Splines and are not raster based.

Thanks for clearing that up. I was probably going on an assumption made by me or heard from someone else that also only thought they knew the right answer.

 

I think I can remember exploding text down to the elements of the characters in one ancient release or another. And it didn't take a particle accelerator, only repetitive explodes. Come to think of it, they may have been made of spline outlines and VERY close diagonal fill lines.

 

(I always thought the lower case "d" txt.shx was the signature AutoCad thing.)

 

I think some Windows compatible TT fonts were available in the 2004 release. One has to be pretty dusty to think of 11 years as "relatively new". Of course, being on the north side of retirement age, to me 11 years ago is like this morning.

[nestly]

Irm, that's pretty interesting stuff. You have any insight why AutoCAD disables antialiasing for TT fonts when the text is at non-zero elevation, or the view target is not zero elevation, or if the visual style is other than 2Dwireframe, etc.

[ammobake]

Some people have posted that this is an issue with the plot preview only but it definately applies to solid hatching in the final product PDF and is an issue in Autocad 2014 as well as some of the newer versions apparently.

 

The fix I used was to use ANSI 37 (cross-hatching) instead of solid hatching and use a miniscule hatch scale (something like .0003).

 

The finished product has no lines this way and everything looks great. I also made sure all my lineweights were 0.

 

On a side-note I think if you are trying to make a high def graphic or logo (like I am) you just create your viewport in paperspace and apply a new, higher "DPI to Raster" value.

 

I didn't experiment with doing this to try and fix the line problem. But it might.

 

-ChriS