Radar mask and alpha channels

  • Ok dumb question time. Can someone explain radar masks to me?

    I want to hide the sweep when it goes outside my map, here, but I have no idea how to do it.

    I have looked at the krpano demo, and seen the radar mask .png, but I am not a Photoshop pro and don't know how to make a graphic like that. And I don't really understand - if the sweep shows through the transparent parts of the mask, what color are the opaque parts of the mask?

    Obviously, I'm not that great with graphics programs.

    Anyway, the point is I would really love a For Dummies tutorial.

  • Hi,

    You can set the size "size =" of the sweep in the example xml I use as below;

    The transparency of the opaque parts of the radar sweep graphic are controlled through the alpha="" , fillalpha="" and linealpha="" above. Just add those into your radar xml and set them as you would like them.

    If you activate the krpano editor setting in your XML

    Code
    <plugin name="editor" url="%SWFPATH%/plugins/editor.swf" keep="true" /></plugin>

    You can use the editor at the bottom of the screen in real time almost, view the XML make any changes to it then select load this xml. It will then use the parameters you just set. Keep playing till you see what you want, then copy the xml portion that works how you like and paste it into the file used to compile your panorama.

    By the way, if you want transparency in an image in Photoshop an easy way is to add a layer below the layer of whatever graphic you have. Dont paint on this layer. Then erase on your graphic layer using the eraser or even the selections tool any area where you want it to be transparent.

    Radar layer -----========---------
    New layer -----------------------------------

    The = signs represent the radar sweep graphic, the hyphens represent the transparency. Save this off in a png format which preserves transparency info and when you load it using your xml code then everywhere that the hyphens are will be transparent. This tutorial should help you a bit more in case I wasn't very good at explaining it *unsure*

    Good Luck

    Rick

    6 Mal editiert, zuletzt von Run (9. September 2010 um 01:57)

  • To have the radar "fade out" over distance, you should use the radial gradient tool in your editor of choice: First, place the center of the radial gradient to the corresponding point on the map, then draw the gradient having it fade from 100% white to transparent. Then use masking techniques (or the eraser) to remove the portions that you don't want "light up" in the gradient.

    It is a rather labour intensive work, but not sure if there's a better way.

    Here's what I created a while back using this technique: http://www.pano.ie/virtual_tours/geraldine_28

  • Success! I finally got it. Thanks to you both.

    So just to explain to any Photoshop dummies like me out there, when you are creating the mask, the portion of the mask you want the sweep to show through should be white. The portion of the mask that hides the sweep should be transparent.

    I think that's what tripped me up, the fact that transparency hides it and opacity lets it show through. It seems backward.

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