How Do I Trace Over A PDF? Suffering from memory loss...

[ctdahle]

I think this is a simple question. Several years ago I started drawing parts for a model airplane so I could cut them on a laser cutter. I had imported a PDF file from https://outerzone.co.uk/ and placed it in a layer. Then I proceeded to trace over the ribs and other parts, turning each part into a block and then moving the blocks to a new file, a cut file for the laser.

This was a great way to learn my way around Q-CAD which I needed to do for a new job. But once I was able to meet the CAD requirements of my employer (We install avionics gear, I design and fabricate instrument panels, brackets and other weird one-off parts) I shelved the modeling project.

But I have been re-infected with the model airplane bug...Here's the problem. I remember that it was difficult for me to make the PDF drawing visible in Q-CAD, but once I changed some settings, I was able to see the drawing.

Seems like it had something to do with settings in the import dialog maybe, or some view setting?

Any suggestions?

[ctdahle]

OK, I figured out how to make the PDF visible: Under the view menu, toggle "DRAFT MODE".

But now I have another problem. The PDF covers/hides all the other layers so that if the PDF is visible, I cannot see the guidelines layer or the layer containing the blocks I have already drawn.

[ctdahle]

Here's my file if anyone is interested.

My process was to draw guidelines around the features of each shape, draw (trace) each part, then convert the tracing into a block and move it to the "Components" layer.

Previously I could see the other layers over the top of the PDF.

RCM Basic Trainer oz8273.pdf.dxf

(109.85 KiB) Downloaded 342 times

[CVH]

Hi,

With an example file we can help you more efficiently, also read above forum rules in red.

A PDF file is a container that can hold various types of data.
What QCAD concerns, that can be vector art and/or bitmaps.

For the first case, QCAD can (re-)import the vector art as vectors, as individual drawing entities or as a named Block with drawing entities.
In the second case it is imported as a picture, as Image entity(ies).

Vectors are stored directly in the DXF/DWG, for images QCAD only stores a link to the image path associated with some properties.
The bitmap data itself is not stored directly in the DXF/DWG.
It may that the image is first extracted from the PDF and saved as a bitmap file, an auto generated name is possible.

Typically we don't see what those images are because we have no copy of those linked files and none are attached.
On top, it is fairly possible that even the referenced path doesn't exist at all on our computers.


In the attached DXF file there are links to 3 Image entities.
- Handle 0x13e ; Block 'Model_Space' ; Layer 'Trace' ; Position (0.0, 0.0) ; Angle 0.0 ; Width-Height factor 0.0025
Linked to C:/Users/ctdah/OneDrive/Desktop/RCM Basic Trainer Project/pdf_images/RCM Basic Trainer Plan_034a5b1900.png
The actual Width and Height are reported as zero or unknown without a copy.

The second is an invalid entry:
- Handle 0x2e9 ; Block 'Model_Space' ; Layer '0' ; Position (0.0, 0.0) ; Angle 0.0 ; Width-Height factor NaN ; Width - Height also NaN (Not a Number)
Linked to C:/Users/ctdah/OneDrive/Desktop/pdf_images/RCM_Basic_Trainer_RCM-501_oz8273_034a5b1907.png
At least fix the Width-Height factors so that it becomes something visible.

The third is inserted in a general user Block:
- Handle 0x216 ; Block 'RCM Basic Trainer Plan' ; Layer '0' ; Position (0.0, 0.0) ; Angle 0.0 ; Width-Height factor 0.0025
Linked to C:/Users/ctdah/OneDrive/Desktop/RCM Basic Trainer Project/pdf_images/RCM Basic Trainer Plan_034a5b1903.png
The actual Width and Height are reported as zero or unknown without a copy.
A Block Reference with Handle 0x217 referring to that Block is inserted in Model_Space on Layer 'PDF' at (0.0, 0.0) ; Scale 1.0 ; Angle 0.0

For ease I listed the Handle, one can select an entity by its Handle with menu Misc .. Select .. By Handle (TH)
Entity handles are persistent and can't be changed that easily.


There is no drawing order related to layers at all
No layer is 'above' or 'below' another layer, it aren't stacked transparent slices in any order.
They are listed in the Layer List in alphanumerical order.

Each drawing entity has its own drawing order, the higher, the more in front.
Entities, including Image entities, automatically receive a drawing order on creation.
Initially one higher as what already exists but things can be re-ordered.
One can alter the drawing order in different ways, one is by simply changing the Draw Order property.
For other methods see menu Modify .. Draw Order ...

For the Image entities: Drawing order of 0x13e = 1 ; of invalid 0x2e9 = 2 ; of 0x216 = 0
The Block Reference 0x217 has drawing order 28 and is more in front, the highest order and the most in front so far.


I can't tell you how you should organize your drawing and what the best tracing method is.
It is common practice to insert a bitmap Image on a dedicated layer and lock that afterwards.
Locking a layer prevents entities that live on it to be selected or just highlighted when near them.
Highlighting also temporarily brings the entity or Image entity to the front what may obscure the rest.
When still unlocked, send any Image to the back (MB) and perhaps apply some fading so that its background is a bit translucent.

Another common practice is to keep your image files in the same path as the DXF/DWG drawing.
Then they become portable as a set, as a folder with: And the drawing file, and the image files.
Also, QCAD will always look for the image file in the DXF/DWG path if it can't find it in the given and stored path.


Recently a new Application Preference was added to not highlight Image entities when near them.
But that won't work out for the Image 0x216 inserted into Block 'RCM Basic Trainer Plan'.
In Model_Space represented by Block Reference 0x217 and the preference applies for images, not for Block References.

At least you could select the Block Reference 0x217 and send it to the back (MB).
Moving it to a layer that is then locked prevents highlighting.

Regards,
CVH