Blog | Importing Single Orthomosaics and Orthomosaic Tiles into Virtual CRASH 6, 5, and 4
If you use applications like Pix4D for photogrammetry, you likely have a need for importing orthomosaic imagery and point cloud data into Virtual CRASH 6, 5, and 4. When importing imagery from photogrammetry, Virtual CRASH gives you 2 options: (1) import the single merged orthomosaic and/or (2) import the image tiles (this is preferred for larger scenes to obtain superior image quality). In either case, Virtual CRASH will automatically import the image data, point cloud data, and any other point measurement data such as ground control points (GCPs). Note, the workflows shown below are illustrated in Virtual CRASH 4, but also apply to versions 5 and 6.
Workflow 1: Using a Single Orthomosaic
If you use photogrammetry software, such as Pix4D, then you’ll love the Smart Alignment Tool (released with the 2019 Summer Software Update). Just load your tfw file and all of your data will import into your scene already aligned! This is illustrated in the video below.
The benefit of this workflow is that it saves on memory resources (more important for Virtual CRASH 4); however, to maximize orthomosaic image quality, you will want use workflow 2.
Workflow 2: Using Multiple Orthomosaic Image Tiles
As of the 2019 Winter Software Update, users of Virtual CRASH 6, 5, and 4 can specify a file folder of image tiles and corresponding .tfw files, and Virtual CRASH will automatically import, scale, and place the individual image tiles in your scene. This allows you maximize system resources where it is needed the most, and produce even more amazing visuals for your case.
(1) Start by placing the large orthomosaic with corresponding point cloud and point array file into same file folder. Make sure these assets have the same file name (they will all have different file extensions of course). In this folder, also include all image tiles and corresponding tfw files. Each tile should have the same file name as corresponding tfw file.
(2) Next, go to Project > Import. Simultaneously select all tfw files in your project folder that contains the orthomosaic and all image tiles. Left-click on “Open”.
(3) Now, you’ll see the Smart Alignment Tool import dialogue box. Set the units and other settings for the various assets you would like to load. Finally, set the image quality you would like to be applied to all images that will be imported. This quality setting will allow you to maximize your system’s resources versus the image quality necessary to generate the best looking visuals.
(4) You’ll then see all assets loaded and automatically aligned. The separate image tiles and orthomosaic will be grouped together. All images have a new parameter “texture quality” which can be set to any value between 1 to 100%. The higher the value, the better the image quality, but the more system memory that is required to use the image. You can modify the texture quality for all images at once, or one image at a time. When modifying the image quality, the best practice is to type in the numerical value into the image quality input field rather than using the slider.
The major advantage of this feature is that you can now fine-tune where you want to keep the highest image quality. For top-down overviews, lower image quality is typically acceptable since the ability to resolve fine details is diminished as the camera is placed further above the road surface. For driver’s perspective visuals, you’ll typically want to use higher quality images for the road surface near the camera. The trade-off between image quality versus system resources is now easily controlled.
A video of the workflow is shown below: