3D printerists.

I would like to print a base 'box' for a CCTV dome camera but it's a
weird half round / elliptical shape.

Whilst I could probably measure it at various intervals and translate
that into Sketchup, I wondered if anyone here had 2D scanned (on a
flat bed scanner) an object to get an accurate profile and then
imported that into their preferred 3D drawing package?

I'd assume you might still have to scale the resultant image (x, y)
but that would be easier than having to draw it from scratch.

The base would simply mimic the base profile of the camera but provide
some space / depth for cables and connectors etc.

This is partly need (for a mate) plus an exercise to see if it can be
done easily (I have no doubt it can be done etc).

(You can buy the bases but they are ~£10+ and you could probably print
20 for that). ;-)

Cheers, T i m

On 20/01/2020 11:30, T i m wrote:
3D printerists.

I would like to print a base 'box' for a CCTV dome camera but it's a
weird half round / elliptical shape.

Whilst I could probably measure it at various intervals and translate
that into Sketchup, I wondered if anyone here had 2D scanned (on a
flat bed scanner) an object to get an accurate profile and then
imported that into their preferred 3D drawing package?

I'd assume you might still have to scale the resultant image (x, y)
but that would be easier than having to draw it from scratch.

The base would simply mimic the base profile of the camera but provide
some space / depth for cables and connectors etc.

This is partly need (for a mate) plus an exercise to see if it can be
done easily (I have no doubt it can be done etc).

(You can buy the bases but they are ~£10+ and you could probably print
20 for that). ;-)

Cheers, T i m


https://alicevision.org

T i m wrote:
3D printerists.

I would like to print a base 'box' for a CCTV dome camera but it's a
weird half round / elliptical shape.

Whilst I could probably measure it at various intervals and translate
that into Sketchup, I wondered if anyone here had 2D scanned (on a
flat bed scanner) an object to get an accurate profile and then
imported that into their preferred 3D drawing package?

I do this quite often for things to laser cut (PCBs and similar). The trick
is to make sure it's 1:1 - in my case the flow is to scan to PDF on a big
office photocopier, which gives me a 1:1 PDF file. Then I import into
Inkscape and trace round the image to produce a clean line that the laser
cutter will accept (it's very fussy).

You can probably do the same, only to produce a path that you then extrude
in your 3D modelling package to make a tube of the appropriate shape.

One thing to be wary of is there's usually a bit of parallax when the item
isn't absolutely flush to the glass, so the output often needs a bit of
tweaking by the odd half-mm here and there. Expect to throw the first one
away.

Theo

On 20 Jan 2020 14:39:06 +0000 (GMT), Theo
wrote:

T i m wrote:
3D printerists.

I would like to print a base 'box' for a CCTV dome camera but it's a
weird half round / elliptical shape.

Whilst I could probably measure it at various intervals and translate
that into Sketchup, I wondered if anyone here had 2D scanned (on a
flat bed scanner) an object to get an accurate profile and then
imported that into their preferred 3D drawing package?

I do this quite often for things to laser cut (PCBs and similar).

Cool.

The trick
is to make sure it's 1:1 - in my case the flow is to scan to PDF on a big
office photocopier, which gives me a 1:1 PDF file.

Ok, I can do that ...

Then I import into
Inkscape and trace round the image to produce a clean line that the laser
cutter will accept (it's very fussy).

Ok. ;-)

You can probably do the same, only to produce a path that you then extrude
in your 3D modelling package to make a tube of the appropriate shape.

Hmm, so is there no 'lasso tool in Inkscape to make that task easier
or would it typically need tweaking in any case?

One thing to be wary of is there's usually a bit of parallax when the item
isn't absolutely flush to the glass,

I have a scanner app on my phone that allows you to do that.

Luckily, in this case I can remove the camera 'ball', clearing the
back of the camera housing of any cables etc and then the base should
stand flat on the bed of my scanner pretty easily.

so the output often needs a bit of
tweaking by the odd half-mm here and there.

I should be happy to make my scan fit the required dimensions in
Sketchup, as long as the scan is a reasonable reproduction of the
basic shape. Luckily, it doesn't have to exact, as long as the camera
sits on there reasonably well and the mounting holes line up etc.

Expect to throw the first one
away.

Whilst I'm happy to do that ... as long as I err slightly (.5mm) in
whatever direction that makes the fit between the things more likely,
I generally find I can even use my first print (even if I sometimes
don't).

In fact that is part of the buzz I still get when designing and
printing things, it's used more like a tool than a hobby now. ;-)

Thanks for the tips, I'll give em a go!

Cheers, T i m

T i m wrote:
On 20 Jan 2020 14:39:06 +0000 (GMT), Theo
wrote:
You can probably do the same, only to produce a path that you then extrude
in your 3D modelling package to make a tube of the appropriate shape.

Hmm, so is there no 'lasso tool in Inkscape to make that task easier
or would it typically need tweaking in any case?

There is a bitmap tracing thingy, but it's not very useful. Automatically
generated lines typically have too many points - that transfers into very
complex shapes you're trying to print. It's better to reduce the number of
points to make a simpler shape. You can set the tool to smooth the edges by
reducing points, but then it rounds off all the corners.

One thing to be wary of is there's usually a bit of parallax when the item
isn't absolutely flush to the glass,

I have a scanner app on my phone that allows you to do that.

Luckily, in this case I can remove the camera 'ball', clearing the
back of the camera housing of any cables etc and then the base should
stand flat on the bed of my scanner pretty easily.

Even 1mm off the glass is enough parallax to make things slightly out.
It's still a problem unless it's perfectly flat.

(scanners don't have a large depth of field, so anything more than a few mm
away will be out of focus)

so the output often needs a bit of
tweaking by the odd half-mm here and there.

I should be happy to make my scan fit the required dimensions in
Sketchup, as long as the scan is a reasonable reproduction of the
basic shape. Luckily, it doesn't have to exact, as long as the camera
sits on there reasonably well and the mounting holes line up etc.

Mounting holes are usually the problem, due to parallax. If you're printing
in a soft material they can often be stretched a bit (regular screws become
self-tapping with enough force It's more of a problem in non-soft
materials (eg 6mm acrylic).

Theo

On 21/01/2020 10:50, Theo wrote:
There is a bitmap tracing thingy, but it's not very useful. Automatically
generated lines typically have too many points - that transfers into very
complex shapes you're trying to print. It's better to reduce the number of
points to make a simpler shape. You can set the tool to smooth the edges by
reducing points, but then it rounds off all the corners.

Many years of making models from scanned drawings has taught me that you
simply measure the relevant dimensions and redraw it.


--
Those who want slavery should have the grace to name it by its proper
name. They must face the full meaning of that which they are advocating
or condoning; the full, exact, specific meaning of collectivism, of its
logical implications, of the principles upon which it is based, and of
the ultimate consequences to which these principles will lead. They must
face it, then decide whether this is what they want or not.

Ayn Rand.

On 21 Jan 2020 10:50:58 +0000 (GMT), Theo
wrote:

T i m wrote:
On 20 Jan 2020 14:39:06 +0000 (GMT), Theo
wrote:
You can probably do the same, only to produce a path that you then extrude
in your 3D modelling package to make a tube of the appropriate shape.

Hmm, so is there no 'lasso tool in Inkscape to make that task easier
or would it typically need tweaking in any case?

There is a bitmap tracing thingy, but it's not very useful.
Ok, thanks.

Automatically
generated lines typically have too many points - that transfers into very
complex shapes you're trying to print. It's better to reduce the number of
points to make a simpler shape. You can set the tool to smooth the edges by
reducing points, but then it rounds off all the corners.

Ok.

One thing to be wary of is there's usually a bit of parallax when the item
isn't absolutely flush to the glass,

I have a scanner app on my phone that allows you to do that.

Luckily, in this case I can remove the camera 'ball', clearing the
back of the camera housing of any cables etc and then the base should
stand flat on the bed of my scanner pretty easily.

Even 1mm off the glass is enough parallax to make things slightly out.

Understood.

It's still a problem unless it's perfectly flat.

In this case it is perfectly flat, it's 'machined' flat in fact and
would be the surface that goes up against the mounting surface so no
extensions or undulations etc. There are some (3) cable exit 'gaps'
around the rim but they wouldn't cause any lifting issues.

(scanners don't have a large depth of field, so anything more than a few mm
away will be out of focus)

Understood. That's why I only suggested flatbed scanning, not scanning
from my camera etc. Ironically, I still have access to the 3D scanner
we built alongside the printer but I thought a 2D scan would be
quicker and more accurate.

so the output often needs a bit of
tweaking by the odd half-mm here and there.

I should be happy to make my scan fit the required dimensions in
Sketchup, as long as the scan is a reasonable reproduction of the
basic shape. Luckily, it doesn't have to exact, as long as the camera
sits on there reasonably well and the mounting holes line up etc.

Mounting holes are usually the problem, due to parallax.

Again, these appear on the same face as the overall section so should
pickup ok.

If you're printing
in a soft material

(PLA)

they can often be stretched a bit (regular screws become
self-tapping with enough force It's more of a problem in non-soft
materials (eg 6mm acrylic).

Understood.

What I would typically do is either overlay what I had scanned with a
geometric reproduction to see how close I was (assuming the original
was created from an engineering drawing) and tweak accordingly or
create my 'best match, do a test shallow print and adjust from that.

Cheers, T i m

On Tuesday, January 21, 2020 at 12:21:45 PM UTC, T i m wrote:
On 21 Jan 2020 10:50:58 +0000 (GMT), Theo
wrote:

T i m wrote:
On 20 Jan 2020 14:39:06 +0000 (GMT), Theo
wrote:
You can probably do the same, only to produce a path that you then extrude
in your 3D modelling package to make a tube of the appropriate shape.

Hmm, so is there no 'lasso tool in Inkscape to make that task easier
or would it typically need tweaking in any case?

There is a bitmap tracing thingy, but it's not very useful.
Ok, thanks.

Automatically
generated lines typically have too many points - that transfers into very
complex shapes you're trying to print. It's better to reduce the number of
points to make a simpler shape. You can set the tool to smooth the edges by
reducing points, but then it rounds off all the corners.

Ok.

One thing to be wary of is there's usually a bit of parallax when the item
isn't absolutely flush to the glass,

I have a scanner app on my phone that allows you to do that.

Luckily, in this case I can remove the camera 'ball', clearing the
back of the camera housing of any cables etc and then the base should
stand flat on the bed of my scanner pretty easily.

Even 1mm off the glass is enough parallax to make things slightly out.

Understood.

It's still a problem unless it's perfectly flat.

In this case it is perfectly flat, it's 'machined' flat in fact and
would be the surface that goes up against the mounting surface so no
extensions or undulations etc. There are some (3) cable exit 'gaps'
around the rim but they wouldn't cause any lifting issues.

(scanners don't have a large depth of field, so anything more than a few mm
away will be out of focus)

Understood. That's why I only suggested flatbed scanning, not scanning
from my camera etc. Ironically, I still have access to the 3D scanner
we built alongside the printer but I thought a 2D scan would be
quicker and more accurate.

so the output often needs a bit of
tweaking by the odd half-mm here and there.

I should be happy to make my scan fit the required dimensions in
Sketchup, as long as the scan is a reasonable reproduction of the
basic shape. Luckily, it doesn't have to exact, as long as the camera
sits on there reasonably well and the mounting holes line up etc.

Mounting holes are usually the problem, due to parallax.

Again, these appear on the same face as the overall section so should
pickup ok.

If you're printing
in a soft material

(PLA)

they can often be stretched a bit (regular screws become
self-tapping with enough force It's more of a problem in non-soft
materials (eg 6mm acrylic).

Understood.

What I would typically do is either overlay what I had scanned with a
geometric reproduction to see how close I was (assuming the original
was created from an engineering drawing) and tweak accordingly or
create my 'best match, do a test shallow print and adjust from that.

Cheers, T i m

I recently scanned a flat 5 sided shape which had three holes, alongside a ruler.
The three holes were in the correct places, or close enough not to matter. The shape needed tweaking.

On Tue, 21 Jan 2020 05:18:16 -0800 (PST), misterroy
wrote:

snip


What I would typically do is either overlay what I had scanned with a
geometric reproduction to see how close I was (assuming the original
was created from an engineering drawing) and tweak accordingly or
create my 'best match, do a test shallow print and adjust from that.



I recently scanned a flat 5 sided shape which had three holes, alongside a ruler.

That's a good idea. ;-)

The three holes were in the correct places, or close enough not to matter. The shape needed tweaking.

Thanks for the feedback.

Maybe I'll actually get time to try it. ;-(

Cheers, T i m