Revisiting the PDF raster vs. vector rendering issue

Joe Dunfee

 In past threads we have discussed the issue of rendered viewports causing the output to be rasterized.  This causes both very large PDF file sizes, and because the line weight settings are ignored for this sort of output, very faint lines. I would use legacy hidden because it generates vector output, except that any curved surfaces come out in a solid color, because of the dense faceting of the curved surface.

I just re-investigated the TrueView Autodesk application and found that it had a number of settings that allow me to tweak it a bit, and I have been able to get more acceptable output.  However, this is still certainly an issue.  So, I am starting this thread to hopefully see if we users can settle on a desirable output, so that perhaps it may guide BricsCAD in future development to improve the PDF output.

One CAD application I used in the past, Space Claim, has the option of overlaying the paper space viewport renderings with vectors.  So, this is a hybrid approach that permits the shading to be done in a relatively coarse raster image with its reasonably small file size, and then the vector lines generate a crisp line.  Of course, a non-shaded, hidden-line removed view, only has vectors. They seem to be able to extract the profile of a cylinder, so that only the perimeter is outlined with the vector lines.

But, a rendering style can still have objects that have color fills, but does not require a raster image. This is because PDFs have the ability to store vector shapes with fills.  For curved surfaces that rely on a gradated color, I imagine it may be possible to break the color up into smaller vector shapes just for the shading.  Ideally, it would be smart enough to optimize the number of facets, so that a tiny object does not require the same number of facets as a large one. And perhaps permit the user to choose the overall facet resolution.

PDFs really are the CAD output medium of the 21st century. Many offices don't even have a large format printer now-a-days. So, it is important to get this working right.

-Joe

Roy Klein Gebbinck

For reference: Joe's previous post concerning this issue:
https://forum.bricsys.com/discussion/29864

Joe Dunfee

 I know there are methods for generating views that show hidden lines as dashed. But, I have not used them, since they do not preserve the colors of the objects, or take on the layer settings of the objects. Though, I am a few releases behind, so there may have been changes since my v14.

I was going to suggest another rendering style, but realize that BricsCAD is limited to using things that AutoCAD uses.

Another topic that came up recently, involves the issue of creating dimensions in paper space.  The problem is that often these dimensions are non-associative or loose their associativity at some point after their creation. And since these dimensions are not in the same space as the model, it is easy to not catch the fact that their value is no longer correct.

Mr. Klein Gebbinck created a LISP routine to find the non-associated dimensions. But, I wonder if identifying the non-associative dimensions and perhaps non-regenerated views might be built into BricsCAD.  It might be done as a notification box that pops up on the lower-right hand side of the screen.  It might list the object categories, with a box next to it to allow you to select the objects.

Joe Dunfee

 I have just noticed an issue, when I am saving PDFs from AutoDesk's TrueView.  Sometimes one of the nodes or end point of a leader will sometimes move on me, quite dramatically.  If the dimension node moves, the actual value changes.  Since it is normally quite an obvious move, it won't cause manufacturing to be wrong, but now I am a bit concerned.  What if the node moves just a little bit?

The problem is intermittent, and even when opening the same drawing file, it may or may not show the problem. Here are some screen grabs to show what I mean. The changes are circled in red.

Since the problem is intermittent, and on the same DWG file, I suspect this is an AutoDesk problem, and not BricsCAD. Has anyone else ever seen this?

-joe

Jumping Dimensions in Autodesk PDF.png

John Gaunt

I have had that in the past within Bcad with Dimassoc=2 - files would open with some dims shifted and associativity lost since closing last.
I have generally/historically used Dimassoc=1 with no problem, since returning to that setting I wouldn't know if the associative problem persists.

Joe Dunfee

 John Gaunt said;

> I have had that in the past within Bcad with Dimassoc=2 - files would open with some dims shifted and associativity lost since closing last. 

I am not clear which program you opened the drawing in. 

I was specifically talking about a PDF where a few dimensions became messed-up.  But, in that case the dimension itself was fine in the DWG opened in BricsCAD. But, now that you mention it, I have also seen dimensions jump around in DWGs before. Though, I had assumed it was because I edited a polyline or something like that.  And, like you, my solution was to turn off dimension associativity.

-Joe

John Gaunt

My problem was completely within Bricscad, either while opening or closing. It's hard to know which.
But it seems to me if Bcad can open a file and misread some dims, perhaps so too could some other program.
If the problem is in the file rather than the program reading it.
I don't know, I'm just answering the question - yes I have seen dims rearrange themselves before.