Semi transparent trees?

[carpalmer]

trying to use new transparency feature on tree images (imported jpegs) to dress up my bldg elevations, but can't get rid off white background around image... any work around? Masking?

Elevations are 2 d / no rendering, just line drawings.

thx

carpalmer

[cbaarch]

if you are using vw2008 designer

you can look for x-frog trees

these work but expect your file to be very large

and

-lines should be used sparingly

use objects to create elevations

use walls for trim

polygons with fills for walls use pattern if printing b/w (which both foreground and background same colour)

windows use polygon with gradient fills etc....

[Charlie_P]

Transparency in a picture file is called it's alpha channel. The tree pictures will need to have the background colours either cropped away or made transparent before you import them into VW - this is because VW sees your picture as a single entity and will vary all of it at once so it's not capable of making the background totally transparent and the foreground partially so.

There are are a number of ways to do this before the picture is imported. To crop it (worst way) get it into an editing program, crop it as best you can, reimport it. You'll still have a bit of the background around the tree because the jpeg will be square, and trees are not unless they've become planks.

Best and in fact only effective way is to give the original picture a transparent background. You don't say what system you've got (Mac or PC) but you need a half good photo editing program (PC/Mac) or a recent iWork program or the Graphic Converter program that used to ship with OSX (Mac only)

Photo editing software such as Photoshop or The Gimp (a free version of Photoshop) allow you to select areas of the picture by the colour of the pixels; you can then select the white background only and delete it. Mac iWork has something called instant alpha which is the same thing but very much easier to do.

Finally. Picture file formats. JPEG as a format has no alpha channel which means that JPEG pictures cannot be transparent. Which ever program you use to knock out the background you'll have to save the result as PNG - Vectorworks is perfectly OK with that and will import it happily; all you'll see is the tree bit and not the sky bit.

If you want precise how-to's then a few system details will be needed...

Good luck,

Charlie

[carpalmer]

thanks Charlie. I'm on XP and fairly profficient with Vectorworks, yet never used Alpha channels (have edited, removed backgrounds, etc.)

Tried the PNG approach but it brought in some background (even though it was deleted in PS)... anyways, if you have it in you to share some more insight, I'll definately look forward to it.

thx

carpalmer

[Charlie_P]

Morning carpalmer,

Sounds like you know your way through this pretty well but I'll go through it in detail anyway...

Open the jpeg in Photoshop; duplicate the background layer; turn off visibility on the original background layer; zoom out enough so you've got a bit of a grey border around the picture.

Using the magic wand tool click on the sky bit; some of it will be selected but probably not all; click on the grey border to deselect; adjust the tolerance value (just tried it with a similar picture and somewhere around 30 works for me); click on the sky bit again; if you've got most of it then change the magic wand tool mode to "add to selection" and click on the remaining bits; click delete. The sky bit should now be grey checkered (photoshop-ese for "there's nothing there"). Goto file, save as - change the format to something with an alpha channel (like PNG) and save.

In VW import the image file selecting PNG for the compression method on the import dialog and all should be well. If there's still some background then more vigorous deleting in Photoshop should clear it; lay the imported image over a black rectangle in VW to see what's actually there.

Some qualifications - I'm using a Mac with VW 2008 right now so there may be some slight differences. Also, I'm pretty clunky with Photoshop - there are ways to get smoother, cleaner results using layer masks and more of the photoshop tools but this is fast & easy... It is possible to get JPEG to do alpha using extra channels, TIFF too, but PNG looks more straightforward to me.

All the best

Charlie

[BG]

When you choose 'print' and the print dialogue box opens, have you tried selecting the 'enable special processing for transparent color bitmaps' option? This worked for us in getting rid of the white background around trees.

BG