Bob, did you think I forgot about you? College football and a sick secondary computer have been my focus. But now it's your turn!
Download this file, as it shows the files that are the end result of a process that is pretty fairly simple.
http://www.fileden.com/files/2011/10/16/3210113//BOB_Work.zip
First step is to make a MAP in SBX. I prefer to rename them to something useful, so in this case I call it BOB.BMP. Notice I renamed the .txt file to BOB.TXT. This allows SBX to place the image in the FSX world.
Most all image editing software works the same, at least for what needs to be done here. I use Paint.Net (free!), but most any other works the same way. Quick terms to remember and hoping the trolls who follow me around don't parse every word and/or term I use, as they are wont to do. Pure BLACK is RGB 255,255,255. Pure WHITE is RGB 0,0,0. The Resample compiler excludes anything that is covered in pure black and includes what is in pure white. I'll cover grays later.
You see the file BOB.bmp covers your little corner of the world. When compiled the whole square shows in FSX. But I wanted something
different, so...I loaded BOB.BMP into the image editor and made a NEW LAYER. Selected the new layer with the magic wand and then used the paint bucket to fill it with pure BLACK. Then I changed to the paintbrush, selected pure WHITE as my color and marked it for
Bob. I delete the original layer (BOB.BMP) as it was only there to size the layer for the Blend mask. After deleting the layer with BOB.BMP on it, I am left with the layer with pure BLACK and
Bob written on it in pure WHITE. My process is to save this new layer with a name BOB_b.BMP. Notice, it's being saved as a BMP file. I then take BOB_b.BMP and use IrfanView to open it. Use menu
Image | Convert to Grayscale, then
File | Save As and give it a .TIF extension. Now it's ready to use in SBX or with the Resample compiler.
Why save the black / white layer as a BMP and convert with IrfanView? Some editors come real close to converting to 8-bit grayscale and TIFF format. Changing it in IrfanView works all the time.
If you have your Map (BOB.BMP + BOB.TXT) in the SBX folder and then copy the blend mask (BOB_b.tif) to that same folder SBuilderX will automatically recognize the blend mask file and include it during compile. The same would apply to a Water mask file (BOB_w.tif), if you so desired. You can see this if you compare the BOB1.INF and BOB2_bm.INF files, where SBX has recognized a file with naming of <original name>_b.tif.
If you open BOB1.bgl with TmfViewer (SDK tool) you will see the entire square displayed. If you open BOB2_bm.bgl with TmfViewer you will see "Bob" displayed. Using the menu View | Show Missing Data Mask with BOB2_bm.bgl will show you how Resample excludes the area in pure BLACK and retains the portion in pure WHITE.
Is a blend mask WHITE painted on BLACK or BLACK painted on WHITE? Whatever floats your boat, as it all comes out the same. If I want most of the area shown in an image, I paint bucket white and paint brush black. Most not showing, I reverse the process.
Life isn't always about black and white, so neither should a blend mask be considered as such. First, having a pure BLACK and pure WHITE blend mask will cause some "dithering" (my term!), which can be described as what happens when you fold a piece of paper and then tear it apart. The edge can be irregular, not like if the sheet had been cut with scissors. To alleviate the dithering, a nice gradient blend can smooth things out between BLACK and WHITE. Since the blend mask is 8-bit we will be working in shades of gray. Where I made "Bob" in the BOB_b.tif file I could hit each of the letters and apply a small-ish Gaussian blur, maybe 3 pixels wide. I might make that Gaussian blur even wider, depends upon what I'm trying to achieve. The darker the gray is to the pure BLACK, the less of it will show through. The lighter the gray is to pure WHITE, then more of the image will show through.
There is no hard and fast rule with regards to how large a gray gradient should be between the pure BLACK and pure WHITE. Tinker with it. There is no hard and fast rule about how big the paint brush should be when drawing on the blend mask layer in the image editor. It can require going down to a real small paintbrush when doing things like coastal rocks.
For the most part, making a blend mask is simple, so long as it's not over-thought. Making a "perfect" blend mask can be complicated, just as any artistic endeavor can become.
Black is excluded, white is retained. Most problems occur with file format errors. What I like with my method is I can compare file sizes and know if the conversion to 8-bit grayscale worked or not. See BOB_b.tif is 1/3 the size of BOB-b.bmp. 8-bits resized down from 24-bits.
A good teacher will not assume a student knows this or knows that. Step by step instructs are best. If you or someone might take the time to do this it would be helpful. Two pizzas and a case of your favorite and a pay raise at work for someone who can do this! Bob (retired teacher- and confused and insane designer!!!!)