Author Topic: Image file tips  (Read 337 times)

Dr PR

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Image file tips
« on: November 28, 2016, 11:10:03 AM »
I have experimented a bit and I discovered that the type of shading or wireframe display affects the colors and shadows in the "File/Image/Save Image File" output.

With a wireframe display colors are muted - like the difference between OpenGL Gouraud and GDI Phong screen display where Gouraud colors are less vibrant. But you can get shadows. See the "focsl wireframe" image (made with shadows disabled).

With an OpenGL Gouraud shades screen image you get the muted colors in the image file but no shadows.

If the screen display is GDI Phong shaded the colors are more vibrant and you get more contrast in the saved image file. See the "focsle Phong" image, again made with shadows disabled.

Notice the difference in color vibrance and light/dark contrast. In particular, look at the dark gray walkway on the deck. I spent many hours playing with materials and colors trying to get this to show in the image files. I was saving the files with a wireframe screen display. On the screen with Gouraud or Phong shading I could get very good contrast between the dark walkway and the gray deck, but this never came out in the image files.

I just discovered yesterday that I have to have the screen shaded with GDI Phong to get the contrast you see in the  "focsl Phong" image. I have been fighting this problem for years! There is NOTHING in the Reference Manual that suggests that you get different image file results depending upon the type of image displayed on the screen!!!!!

****

Images with shadows are another thing. Don't even try to save an image with shadows without Phong shading on the screen.

With a wireframe screen image for full drawing image files the shadows may be pretty decent if you use the 2048x2048 shadow map, but if you zoom in on a part of the drawing the shadows in the image will be "chunky" and very ugly if you use "old shadows." If you enable the "Use new shadows" option in the "Options" menu you may find that only the left side of the saved image will have shadows.

If you use the "new shadows" and Phong shading on the screen the shadows will look very nice. See the "Phong screen capture" image. Notice the sharp edges to the shadow of the anchor on the side of the hull.

However, these nice shadows do not appear in the "File/Image/Save Image File" image. See the "focsle Phong shaded new shadows" image. Notice how the edges of the anchor shadow are fuzzy and blurred. All the other shadows are just as fuzzy. But at least you get all the shadows and not just in part of the image.

I could see no difference between "new shadows" and "old shadows" in the image file output. So apparently there is no way to get sharp shadows in an image file like the sharp shadows in the Phong screen image. The only option for sharp shadows over the entire image is to use screen capture and open the saved image in a photo editing program. Unfortunately, this limits us to the very low pixel size screen images. But at least we can zoom in on small details in the drawing on the screen and get decent shadows.

However, even in the screen capture image there is a problem - some shadows are missing. On the left side of these pictures there are two large cylindrical ventilators. In the fuzzy "focsle Phong shaded new shadows" image the upper ventilator has a shadow. In the screen capture with the sharp shadows the shadow is missing behind this ventilator.

My experience with the "new shadows" is that sometimes there is an arbitrary division between the lower left and upper right corners of the image, and on the upper right side there will be no shadows. The angle and position of this division seems to depend upon the view angle, lighting angle and amount of zoom for the view in the drawing.

With "old shadows" the Phong shaded screen image does show the missing shadow, but the shadows are fuzzy like in the "focsle Phong shaded new shadows" image.

My guess is that "new shadows" aren't being used in the image file output even if they are enabled in the "Options" menu.

Let's hope that the new RedSDK video code resolves these issues!

Phil


« Last Edit: November 28, 2016, 11:26:07 AM by Dr PR »
DesignCAD user since 1987

Dr PR

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Re: Image file tips
« Reply #1 on: November 28, 2016, 10:44:31 PM »
Here is an example of missing shadows with "new shadows" enabled. They are clipped inside the image area, parallel to the top edge of the image, but angled to the right edge at the same angle as the shadows.

The angle of clipping seems to be dependent upon the height and angle of the light source. I think the light source had a Horizontal Angle of -9 and a Vertical Angle of 17 for this image with the "Move with eye" option enabled.

The shadows that are there are very good.

Phil
« Last Edit: November 28, 2016, 10:55:07 PM by Dr PR »
DesignCAD user since 1987