This document provides some general guidelines you might find useful as you create artwork for your panels and gauges. It assumes you have some general familiarity with graphic design and associated tools.

Tips on Creating Art for Panels and Gauges

See Also

• SDK Overview
• Creating XML Gauges
• HelpIDs
• GPS Variables
• Panel Configuration Files
• Programming C++ Gauges
• Tooltips

Table of Contents

• Background
• Creating a Layout for the Panel
• Beginning Production
• Building the Gauges
• Using the Psd2Xml Tool
• Using Imagetool with Gauges

Background

In ESP 2-D art is used to represent the aircraft panels in non-Virtual Cockpit mode. The panel is broken down into many files stacked on top of one another. The cockpit background is a separate bitmap that has the individual gauges placed over it. Currently, the shadows of the gauges are placed on the panel background. The gauges themselves are not realistically three-dimensional and do not represent accurate depth relationships. This limitation is deliberate because it gives you the ability to position the gauges on the panel wherever you prefer.

The most important feature of a Panel system is its readability. The panel should not only be convincing, but it must look acceptable at any resolution. You should create a set of art at 1024 x 768 resolution. Lower resolutions are not supported.

Learning about the Aircraft

Before beginning work on a panel, you should have a good understanding of what you will be working on. Familiarize yourself with the aircraft and its capabilities. Gather as much information as possible on the panel. Once you have gone through the reference material for the aircraft, compare the panel with those of other aircraft. You will always have to create the background of the specific cockpit, but sometimes you can use gauges from a different panel. These gauges may resemble the gauges for your aircraft even though they are not an exact replica. Originality is always important, but sometimes choosing a generic gauge background and the re-use of gauges can save a lot of time, especially in building prototypes.

Creating a Layout for the Panel

Researching the Instruments

Now start thinking about the look and feel of the cockpit. Find out which instruments you should include in the layout. Create a priority list of instruments and go through it with anyone with knowledge about what’s important to include in the cockpit. Talk with pilots and get an idea of what people want to see. Unless you know a fair amount about aviation, you may overlook something that is critical for efficient flight or navigation.

Creating the Layout

Once you have a list of what needs to be included on the panel, create a layout of what the panel is going to look like. The layout can be the most difficult part of creating a panel. However, the goal of the layout is very simple: you want the panel to retain its original look and feel while allowing the most space for instruments. Even a few pixels can make a difference when making room for instruments. Make sure that all the instruments stay in proportion to each other and with the panel background. Remember, this is only a layout and it can look a little rough. Some artists like to create layouts by drawing them, while others find that cutting and pasting the raw photographs, using photo editing software, is easier.

One concern you may have when you create a layout will be the height of the panel. A panel that is too high will decrease visibility for the user. Creating a panel taller than 50 percent of the screen can be acceptable if it is a better representation of the real-world layout, though 50 percent of the screen height is a good limit to try to keep the height of the panel under.

The slope of the panel’s sides is another thing to consider. If the sides are pitched too steep, performance will be lost due to the larger 3-D window. Raising the 3-D window a few pixels can increase performance. If the sides are not pitched very much, the panel will appear flat, without dimension.

Beginning Production

Creating the Base Background

You may want to begin with the panel background. This piece of art can take a long time to create, especially when it is your first or second panel. Make sure that you spend the time needed in making the background seamless. Use layers to your advantage in creating depth. If the photograph that you work with is too difficult to clean up, use flat colors to make the background’s base. Then add a gradation, usually lighter on top to darker on the bottom, and some sort of noise or texture to give more depth. You can often achieve similar results by cleaning a photograph of a background with filters and gradation.

Once the base has been established, add subtle depth and detail. Scratches, nicks and paint chips can add a lot of character and realism to a panel. Over time, you may want to create a library of such details. Apply them through the aid of opacity and layer options. Each case is different. Experiment with what looks best.

Merging the Side Panels

After you have established the base background, begin working on how the side panels will merge into the background. Often, you can place a seam or crack over the two layers, which helps blend the two together. You can take these cracks or seams from any cockpit photograph; otherwise, you may have better luck drawing a seam, although you may find that drawn cracks often appear a bit too perfect.

Creating the Panel Edge and Shadow

Over the base background and sides will be the edge of the panel and its shadow. Make the edge of the panel as thin as possible without sacrificing the cockpit’s character. A thin edge can look wimpy, while a thick edge, as real as it may be, will be a waste of space. You may want to keep these two elements as separate layers for flexibility in making changes later.

Shadows are usually between 50 percent and 60 percent opacity, which gives the panel depth but does not create shadows that are too overpowering. The default lighting typically represents an overhead softer light source (for example, a hazy day at noon). If you choose a direction of light, note that it may not match the outside of the plane or landscape.

Compressing the File

When the panel background is close to complete, make a copy and compress it into an 8-bit file. If banding occurs in the shadowed areas, you may have to lighten or darken the shadow to make it look smooth. This, of course, will vary depending on which program you use to compress your files into 8-bit.

Building the Gauges

Separating the Gauge Elements

When creating instrument gauges, try keeping as many elements separate as possible. This will enable you to easily add library elements to your instruments without having to do a lot of work.

Working at a Larger Size

You’ll probably find it useful to work in a larger size than that which the gauge will be resized to. If appropriate, start with the original scanned photograph and work from a copy. This will be helpful as you clean up the instrument and still need a reference.

Cleaning the Rings and Backgrounds

The first thing to do is clean up the ring and background of the instrument. Make sure the lighting remains even across the ring (with no hot spots from the lighting). Hot spots give a false impression of where the sun is coming from.

Keep as much detail as possible, which gives the gauge character. Create a copy of the inside of the gauge (the gauge face) where the glass covers it, and make this a separate layer. Remove the inside of the gauge from the original layer to clean up the edge of the ring. Now you can lighten or darken the gauge background without changing the tone of the inside.

Adding Depth and Details

Working on the inside the gauge face, remove the needle and make it into a separate layer. Next, clean up the existing art, or lay down a color, then add a texture or noise on top to add depth. You may want to apply a different “clouds” filter to the gauge face to make it look a little more natural. With the ring layer over the face layer, create a little drop shadow from the ring to add depth to the gauge. Make sure this is on a separate layer for flexibility. You may want to add a light-black Gaussian-blurred ring over the gauge face to show that it has a round feel to it. These are subtle features that add reality to the artwork.

Now create another layer. With the original raw photograph as a guide, draw the tick marks of the instrument. Try to make these tick marks bright and readable so they stand out when you resize the gauge later. Finally, return to the needle layer and strip the needle from the background. Make sure that the tonality of the needle does not blend into the new gauge face.

Compiling the Gauge

To compile your gauge, create another layer and merge all of the gauge elements, except for the needle, into that layer, while retaining the existing elements. Once you have done this, you have a compiled gauge and all of its elements and its separate needle are ready for resizing.

Resizing the Gauge

Make sure that you save your work before you begin resizing. If you need to make any adjustments to the gauge, you can change the element and then re-merge that element onto the compiled layer without having to repeat a lot of work.

1. Make a copy of the compiled instrument layer and place this into a separate file.
2. Copy the needle into the new file to resize both at once.
3. Resize the file to 1024x768 resolution.
4. Now, add the type to the gauge (referring to the larger original file for reference). Explore the fonts on your computer and choose one that matches the typeface of the gauge.
5. Create another layer and merge the compiled gauge with the type layer. Sharpen this layer and the needle layer. Save this file for any future adjustments.
6. Next, make the two layers into separate files. When making these separate files, clean up the edges of the file by giving it an aliased edge. It will save time later when you compress the 24-bit file to 8-bit.
7. Make the backgrounds of the files true black (0,0,0 RGB value). True black appears transparent in the simulation.
8. Place these files into a separate folder, which represents the 1024 art ready for 8-bit conversion.

Palletizing the Artwork

You can use a number of programs to palletize your artwork, it is educational to try several before deciding. Different pieces of the artwork do not need to use the same palette. Once you’ve converted the files to 8-bit, save them as a separate file and place them in a folder labeled “Completed Art” (or something that lets you know the art is ready for final use).

Check to see if pixels with the values of 0,0,0 and 1,1,1 are where they should be.

Creating a Final Composition

Once all the artwork is complete and has been resized to both resolutions, assemble the artwork into a final composition for the entire panel.
Double-check to see if there are any mistakes or if something doesn’t look right. It is inevitable that you will have to change something. Make the appropriate adjustments and then add the new artwork to the final composition.

Using the Psd2Xml Tool

Psd2Xml is a tool that generates the files required for a gauge from a multilayered Adobe Photoshop image (.PSD file).  The files output are a set of .BMP files (one for each layer in the .PSD) and a skeleton XML file. This tool is located in the Panels and Gauges SDK folder.

To run the tool from the graphical user interface (GUI), start it and select the PSD file you want to convert.

To run the tool from the command-line, use the following syntax:

psd2xml [/o=<dir>] <input.psd>

The optional /o flag specifies what directory the generated files should be output to, otherwise they are output to the same folder as the input file.

Notes on using the Psd2Xml tool:

The tool ignores layers that are not currently set to "visible" in Photoshop.

The name of a layer becomes the name of the .BMP file. For each .BMP file, an <Element> with an <Image> by that name will be generated in the XML file.

If there is a channel in the PSD file with the same name as the name of a layer, the pixels of the channel areinterpreted as follows:

• a pixel with the value 255 (white) means the corresponding pixel in the BMP file will be an image pixel;
• a pixel with the value 128 (gray) means the corresponding pixel in the BMP file will be a mask pixel (1, 1, 1);
• a pixel with the value of 0 (black) means the corresponding pixel will be transparent pixel (0, 0, 0). 
• use this method to generate mask bitmaps for use within the panel system.

For elements which rotate (needles and knobs for example), you can specify the axis in Photoshop. Place an anchor point with pen tool at the rotaion point of the element and give the path the same name as the layer.  This will automatically generate the <Axis> property definition.

For elements which rotate, you can also specify the tip point. Use the pen tool to put a second anchor point at the tip.  This will define the default orientation of the rotating element.

If a layer has the same name as another layer, with "_window" or "_mask" appended to the end, in the generated XML, the mask layer will be a <MaskImage> and paired with the matching <Image>.

Psd2Xml Sample

If the tool psd2xml is run with the sample .psd file provided ( from the command line type psd2xml Psd2XmlSample.psd) the output is Psd2XmlSample.xml plus some bitmaps.  If you then open Psd2XmlSample.xml in the ACE gauge editor, it will display the gauge elements and just require a bit of editing in order for the gauge to function in the simulator:

Using Imagetool with Gauges

Imagetool includes many methods for manipulating images used in ESP. However, most of those features are used for other areas of the simulation besides gauges (terrain, etc.). Gauge developers can, however, create images of the correct format for gauges by using Imagetool.  The major uses of Imagetool for gauge developers are as follows:

• Convert .psd’s to the proprietary .bmp-with-alpha format
• Convert a .psd to a .bmp with mask pixels, based on the image’s alpha channel.
• View images created with ImageTool.

Imagetool is also an easy way to determine the format of an image.

Converting .psd’s to .bmp-with-alpha format, maintaining alpha channel

There are two ways to do this: by running the tool from the graphical user interface (GUI) or the command-line.

GUI

1. Open the file by using the File->Open menu command.
2. In the Image->Format menu, choose the format you wish to convert to (8-Bit).
3. Save the file by using the File->Save menu command.

Command-line

1. Open a command window by running “cmd.exe” from the Start->Run dialog. 
2. From the command line, run “imagetool –gaugealpha [filename]” where [filename] is the name of the file you wish to convert. (Note: This flag is not documented in the Usage guidelines that appear when “Imagetool -?” is run.)  By default the .bmp file generated will have the same name as the .psd from which it was created. The image generated will be 8-bit (palletized).

After converting the image to .bmp-with-alpha format by using one of the two methods above, you can view the alpha channel in imagetool.

Converting .psd’s to .bmp-with-alpha format, creating a “gauge image”

When a “gauge image” is created, the alpha channel’s pixels are altered as follows:

• If a grey pixel has a value greater than or equal to 148, it is converted to white, which indicates an opaque pixel. 
• If it is between 108 and 147, it is converted to grey, which indicates a mask pixel.
• Pixels with values less than 108 are converted to black, which indicates a transparent pixel. Additionally, the RGB channel is modified so that transparent pixels are black and mask pixels are of RGB value 1,1,1.

There are two ways to create a “gauge” image: by running the tool from the graphical user interface (GUI) or from the command-line.

GUI

1. Open the file by using the File->Open menu command.
2. Select the Image->Make Gauge menu item.
3. Save the file by using the File->Save menu command.

Command-line

1. Open a command window by running “cmd.exe” from the Start->Run dialog. 
2. From the command line, run “imagetool –gauge [filename]” where [filename] is the name of the file you wish to convert.  By default the .bmp file that is generated will have the same name as the .psd from which it was created. The image generated will be 8-bit (palletized).

After converting the image to .bmp-with-alpha format by using one of the two methods above, you can view newly created image and its alpha channel in imagetool.

Viewing images created with ImageTool

Because of the unique file format (.bmp-with-alpha), ImageTool is the best way to view these images. The default view in ImageTool displays a combination of the alpha channel and the RGB channels. The way this alpha channel is applied depends on the way the image was created:

• If the alpha channel was maintained during the file conversion, the alpha channel is applied in the following manner:  the brighter the pixel in the alpha channel, the brighter the RGB pixel is drawn. 
• On the other hand, if a “gauge image” is viewed, the alpha channel is not applied in the default view – only the RGB channel is visible.

To view the alpha channel separately, choose the menu option View -> Alpha Channel.

Determining the format of an image

To determine the format of an image, click on Image->Format in Image Tool.