SketchUp Ground Polygons
SketchUp is often overlooked as a legitimate design tool for Flight Simulator, largely because it lacks integration with the ACES toolset. While that inhibits some important functionality, namely in terms of material attributes, SketchUp (SU) offers some powerful features that are simply not found in other 3D modeling programs. The feature that this article will focus on involves SU's ability to integrate with Google Earth and include position data with exported models. Another very important feature is SU's ability to work with most relevant file formats, including Photoshop .psd files. Bear in mind that SU has no native capacity to manipulate .DDS files; if that is your intended format for completed textures, you will have to make allowances. I use FSXA, Photoshop CS 5.1 and SketchUpPro 2013. Many of these techniques will work with other versions and software, but it would be up to the user to make the required adjustments.
Arno published an excellent tutorial about using SketchUp to model your house in Flight Simulator. It is assumed that you are familiar with that process and we will start by expanding upon the ability to geographically locate your model. In this article we are going to again invoke the geographic placement tool of SU and this time we will use it to create and place a ground polygon. For this particular demonstration, we have access to high quality ground images of the area we want to improve. You may ask why we don't simply compile the images into a photo derived scenery .bgl; we could, except the quality is so high, it would take days to compile and the photo ground .bgl would be too immense to be practical. Another very good way to create high quality ground polygons would be to use the tool found in Airport Design Editor, the difference being that these ground .bgl's are able to be manipulated using a scenery placement program. I use Instant Scenery 3 and within the Flight Simulator interface, I am able to precisely place, observe and adjust these ground polygons. I can use the "line of objects" function to make a hold short line from a single "element" and I am able to minutely adjust elevation to both expose tires and conceal lower layers.
In our example, we have a customs box with a dubious looking Dash-8 awaiting inspection. The photo ground .bgl depicts the dashed outline of the box well enough, but only hints at the contained text:
Our first step is to create the image to cover and effectively replace the customs box. I tried to cut the border right through the dashed lines to use the contrast to obscure the transition between my ground polygon and the underlying photo .bgl. Once you have an acceptable image, save it in .psd format. Next open SU and use the Add Location function to get a Google Earth snapshot of the area you intend to modify:
Now locate your .psd file and import it directly into the SU scene. Upon importing, you will have to stretch and rotate it to fit exactly over it's coverage area shown in the Google Earth snapshot. I should make a note here that the crisp letters were derived by editing the .psd file before saving:
After that you can unlock and delete the Google Earth snapshot. Previously I wrote that you must highlight your imported .psd and select "use as texture," however this is not required. Now you can export your "model" in Collada .dae format to convert it using Model Converter X. In that program, open the Ground Polygon Wizard and import the .dae. Un-check the slice and group polygons boxes, unless your polygon is exceptionally large. The slice polygons check box is useful if your polygon is a runway or something large that may be subject to Earth curvature and using the check box will prevent flickering near the middle of the large polygon. Bear in mind that the consequence is the polygon will have many shards that have to be aligned manually using this technique.
Remember to also select the convert textures check box and define a saved location. After clicking convert, use Model Converter X to import the compiled .bgl, then use the scenery objects editor to export all the contained models in .mdl format. Now use Model Converter X to open your intended scenery library .bgl, or import one of the exported models; then use the scenery objects editor to add any remaining models. Now export this as a scenery .bgl and you are ready to place within the Flight Simulator interface.
Here we see the ground polygon in place under the Dash-8. The words are clearly legible, even from this zoom level, but the color is somewhat off and the customs box looks exactly like what it is, added:
No problem - and this is one of the neat things about working with these three programs. Go back to the original .psd and open it in Photoshop. Here I have taken the "Hue/Saturation" adjustment of Photoshop and moved one value to the extreme. Now export this to .dae; import to the Ground Polygon Wizard, convert, then copy the compiled texture to the working texture folder. Since the texture mapping is unchanged, the ground polygon will have the new textures next time you open Flight Simulator. This version seems to make a nice representation, close enough, and one could spend the effort to get a virtually seamless match:
Now we can again examine our ground polygon in sim:
Looking closer, we see that the letters are perfectly legible:
Even closer, we see that the Dash-8's tires are fully exposed. If they we partially obscured, we could slightly adjust the polygon elevation to compensate:
This substitution technique is not limited to edited textures. Say, as an example, you selected an area of your model to apply a night texture, or for another reason, the texture mapping on your edited model no longer matched the model that has already been placed in scenery. Using the LOD tool of Model Converter X, one can delete the physical model and retain the GUID and placement data. Then by importing the edited model at the same LOD, then exporting as a scenery .bgl, you will see your new model in place of the old one within sim, so long as you remembered to export the new textures to the active texture folder.
