Terrain Tile Texture Production: Overview of the Process

Transcription

1 Page 1 Terrain Tile Texture Production: Overview of the Process Last updated: 4/6/2010 9:02 PM CONTENT PIPELINE AREA: Terrain Tiles AUTHOR - ORIGIN: Peter Lewis (petlewis) STAKE HOLDERS: RELATED DOCUMENTS: TrainSim, ESP, Flight Sim, CORE To follow 1. Overview All of the Simulation products built on Microsoft ACES Studio game and Microsoft ESP Simulation training platform use the built in terrain system and supporting Autogen systems to fill out the world with rich visual details. Whether your mission takes place in one of the many high detail environments created for the products or takes you out into one of the remote areas of the planet outside of these special areas, your experience will be filled with the same rich terrain details that will make keep you immersed in the believability of the simulated world. With TrainSim2 and ESP v.2 we have taken the terrain details to the next level. With this newly developed terrain technology we not only maintain the rich experience already familiar to Flight Simulator fans as they fly over the terrain from 10,000 ft, but we now provide a seamless transition to an equally rich experience at the up close and personal distances required by the ground level simulation of our Trains and the World Of Rails in Train Simulator 2. As Part of this new system, we will be re-authoring our terrain tile textures to work with the new terrain technology. This document will give you an overview of the whole Terrain Tile production from removing 3D visual information called Tile Flattening, through each phase of process of reintroducing the 3D details back into the world via Detail Look-Up Textures and the Autogen Annotator Tool.

2 Page 2 2. Introduction to the New Terrain Tile Process In order to make the experience at the ground as rich and detailed as the Flight Simulator high altitude experience we ve provided in the past we have made some changes to both how the terrain tiles are authored as well as how the game engine manages and renders the new textures to the ground surfaces. As you can see in the image above the Aerial Photo based terrain tile A looks great from the air shot, B, but once the player reached the ground the pixilated details in shot C really destroy any feeling of this being a real ground surface. In the shot below with the flattened terrain texture applied to the ground and an appropriate detail texture blended in with the tile texture you can see that the visual experience is much closer to what one would expect to see at this close range.

3 Page 3 Once buildings and vegetation is placed into the scene either as unique objects or through the Autogen system (an automated system for distributing geometry throughout the world) then the ground experience will accurately reflect the perceived Three-Dimensional world seen from the air. This early screen shot from Train Simulator 2, currently in production, shows a flattened Urban Terrain Tile with the 3D Objects in place. Once shadows are added to the ground this will create an even more compelling user experience at or near the ground. 2.1 Goals of Tile Flattening Procedures 1. Remove all Three Dimensional Elements What you are trying to create is a texture that represents the ground on which all of the 3D elements (buildings, vegetation, and vehicles) are built on top of. You are essentially taking an aerial photograph and turning it into a ground texture. 2. Make all tiles in a tile set seamlessly align Make all tiles within a tile-set (the number of tiles per set varies) seamlessly match along the edges defined as tileable Each tile set has a tiling pattern associated with it that tells the game engine what tiles it can place next to each other to create a seamless landscape that doesn t produce any noticeable tile artifacts. 3. Define the surface type. A detail texture gets blended into each distinct surface type (grass, cement, etc) determined by a detail look up texture. A detail look up texture, based on the underlying flattened tile tells the game engine which type of detail texture to blend into each area of the terrain tile. 4. Define what type of 3D objects get placed on each tile (Annotations)

4 Page 4 Tells the Autogen system what sets of 3D objects should be place in a defined region of the tile texture. How it should be aligned with the underling texture Based on the underlying Terrain Tile 5. Provide Seasonal variations for every terrain tile The game engine provides the mechanism for changing the look of the world based on the seasonal variations appropriate for the land class type and the region of the world. There are 5 seasonal variations; Summer (the original flattened texture), Fall, Winter, Hard Winter (snow on ground), and Spring. 2.2 Tools The following is a list of all the tools that will be required during each phase of the process. Flattening the Tiles o Photoshop CS3 PS Actions (Provided by Aces team) PS Scripts (Provided by Aces team) o Build of Game (To check work) Debug Tools (for populating terrain in-game with tile set to be checked) Detail Lookup Textures o o Photoshop CS3 PS Actions (Provided by Aces team) PS Scripts (Provided by Aces team) Build of Game (To check work) Debug Tools (for populating terrain with tile set to be checked) Blend Masks o Photoshop CS3 o Build of Game (To check work) Debug Tools (for populating terrain in-game with tile set to be checked) Annotations o Annotator Tool o Build of Game (To check work) Debug Tools (for populating terrain in-game with tile set to be checked) Seasonal Variations o o Photoshop CS3 PS Actions (Provided by Aces team) PS Scripts (Provided by Aces team) Build of Game (To check work) Debug Tools (for populating terrain in-game with tile set to be checked) 3. A Closer Look at the Process To help you get a better understanding of the procedures used during this production here is some supporting information on each phase of the process. 3.1 Land Classes The global land cove in our Simulator products are derived from the Olson Global Ecosystems dataset and modeled on a spherical earth.

5 Page 5 The following is a table of the Modified Olson Land Classes on which the land class tile sets described in this document are based. Each of these land classes will also have regional variations as well to capture some of the regional diversity within a give land class. 0 Ocean, Sea, Large Lake 51 Semi Desert Shrubs 102 Lrg City Urban Grid Dry 1 Large City Urban Grid Wet 52 Semi Desert Sage 103 Lrg City Urban Non Grid Wet 2 Low Sparse Grassland 53 Barren Tundra 104 Lrg City Urban Non Grid Dry 3 Coniferous Forest 54 Cool Southern Hemsph Mix Forests 105 Medi City Urban Grid Wet 4 Deciduous Conifer Forest 55 Cool Fields And Woods 106 Med City Urban Grid Dry 5 Deciduous Broadleaf Forest 56 Forest And Field 107 Med City Urban Non Grid Wet 6 Evergreen Broadleaf Forests 57 Cool Forest And Field 108 Med City Urban Non Grid Dry 7 Tall Grasses And Shrubs 58 Fields And Woody Savanna 109 Lrg City Suburban Grid Wet 8 Bare Desert 59 Succulent And Thorn Scrub 110 Lrg City Suburban Grid Dry 9 Upland Tundra 60 Small Leaf Mixed Woods 111 Lrg City Suburban Non Grid Wet 10 Irrigated Grassland 61 Deciduous And Mix Boreal Forest 112 Lg City Suburban Non Grid Dry 11 Semi Desert 62 Narrow Conifers 113 Med City Suburban Grid Wet 12 Dry Crop and Town 63 Wooded Tundra 114 Med City Suburban Grid Dry 13 Wooded Wet Swamp 64 Heath Scrub 115 Med City Suburban Non Grid Wet 14 ### Unused ### 65 ### Unused ### 116 Med City Suburban Non Grid Dry 15 ### Unused ### 66 ### Unused ### 117 Sml City Suburban Grid Wet 16 Shrub Evergreen 67 ### Unused ### 118 Sml City Suburban Grid Dry 17 Shrub Deciduous 68 ### Unused ### 119 Sml City Suburban Non Grid Wet 18 ### Unused ### 69 Polar And Alpine Desert 120 Sml City Suburban Non Grid Dry 19 Evergreen Forest And Fields 70 ### Unused ### 121 Lrg City Highrise 20 Cool Rain Forest 71 ### Unused ### 122 Ice 21 Conifer Boreal Forest 72 Mangrove 123 Inland Water 22 Cool Conifer Forest 73 ### Unused ### 124 Ocean Inlet 23 Cool Mixed Forest 74 ### Unused ### 125 Non Perennial Inland Water 24 Mixed Forest 75 ### Unused ### 126 Non Perennial Inland Sea 25 Cool Broadleaf Forest 76 Crop And Water Mixtures 127 Reef 26 Sthrn Deciduous Broadleaf Forest 77 ### Unused ### 128 Grass 27 Conifer Forest 78 Sthrn Hemisphere Mix Forest 129 Arid 28 Montane Tropical Forests 79 ### Unused ### 130 Rock 29 Seasonal Tropical Forest 80 ### Unused ### 131 Dirt 30 Cool Crops And Towns 81 ### Unused ### 132 Coral 31 Crops And Town 82 ### Unused ### 133 Lava 32 Dry Tropical Woods 83 ### Unused ### 134 Park

6 Page 6 33 Tropical Rainforest 84 ### Unused ### 135 Golf Course 34 Tropical Degraded Forest 85 ### Unused ### 136 Cement 35 Corn And Beans Cropland 86 ### Unused ### 137 Tan Sand Beach 36 Rice Paddy And Field 87 ### Unused ### 138 Black Sand Beach 37 Hot Irrigated Cropland 88 ### Unused ### 139 Airfield1 38 Cool Irrigated Cropland 89 Moist Eucalyptus 140 Airfield2 39 ### Unused ### 90 Rain Green Tropical Forest 141 Rock Volcanic 40 Cool Grasses And Shrubs 91 Woody Savanna 142 Rock Ice 41 Hot And Mild Grasses And Shrubs 92 Broadleaf Crops 143 Glacier Ice 42 Cold Grassland 93 Grass Crops 144 Evergreen Tree Crop 43 Savanna (Woods) 94 Crops Grass Shrubs 145 Deciduous Tree Crop 44 Mire Bog Fen 95 Grass Skirting Desert Rock 45 Marsh Wetland 96 Grass Skirting Savanna Grass 46 Mediterranean Scrub 97 Grass and Shrub Skirting 148 Non Mountain Rock 47 Dry Woody Scrub 98 Dry Grass and Dirt Skirting 149 Cool Dry Conifer Forest 48 Dry Evergreen Woods 99 Sand and Desert Skirting 150 Cool Dry Conifer Forest Meadow 49 ### Unused ### 100 Ocean, Sea, Large Lake 50 Sand Desert 101 Large City Urban Grid Wet

7 Page Flattening of the Tiles As mentioned earlier in this document the flattening process is essentially just removing all of the 3D elements from our current tile sets. Additionally some elements such as roads will likely need to be repaired by rebuilding road edges or sections that had previously been covered by 3D elements (most commonly trees with canopies that extended over the road). While this process sounds like a laborious and time consuming process our team has come up with a number of processes that can partially automate certain aspects of the flattening. Certain land class types lend themselves to automation better than others, but we will provide guidance in areas where there are time saving procedures that are effective. Automation The following is an example of the type of using a simple but effective Photoshop blending method to flatten a whole range of 3D elements by applying a single layer to the aerial imagery. 1. The following image is the original FlightSim terrain tile.

8 Page 8 2. Using a pattern layer that one of our in-house artists created, they inserted the layer, shown below, above the original tile image and set the blending method for the layer to Lighten 3. The result, below, is an image where the high contrast shadows of the original image have been crushed with an organic, modeled quality that reads to the eye like the trees have been removed.

9 Page 9 We will document many of the methods that we have found to be effective, and I m sure your team will discover their own methods for automating some aspects of the flattening process. Tiling Part of the process of flattening the tiles will be to make sure that the edges that need to be aligned in game will do so seamlessly. Many tile sets will contain tiles that can all tile perfectly to themselves and all other tiles in their tile set, however, there are a number of tile sets that contain blocks of tiles that must always be put down together. The most basic level of tiling, and the most common in our system of land class tiles is the tile that tiles to itself and all the siblings in its tile set. We use a Tile Pattern texture to determine how to distribute the tiles in a given set. If the tile set above contained seven tiles the distribution pattern might look something like the image below.

10 Page 10 Additionally we have some tile sets that contain blocks of tiles that are meant to always be placed as a group. In this case we have created a distribution pattern something like you see in the image below. Note how Tile A and B create a block but that the A/B block tiles with the other tiles in the set as well. We use a variety of different Tile Patterns to populate the world s terrain. Each Land class tile set is hard coded to tile using one to the available patterns. As part of your production pipeline you will have to make sure that all tiles in a tile set align seamlessly based on the Tile Pattern that we supply with each tile set.

11 Page Creating Detail Look Up Textuers An important component of our new terrain tile technology is the use of detail maps, highresolution images that get blended into the terrain at runtime. Terrain tile textures that are being used are of low resolution. Each pixel represents 1 square meter of real world land. As a result, the land looks blurry when viewed at or near ground level. Detail maps are used to "multiply" on top of the diffuse map (terrain texture) with a higher resolution tiled pattern. These detail textures will be identified as specific colors coded in the Detail Atlas (below). o The detail lookup textures are authored as an indexed color texture. At runtime each indexed color pixel will tell the game system to apply a corresponding detail texture to that pixel on the landclass texture. Part of the production process will include creating these detail lookup textures. Like the other steps in creating a complete tile set, we will provide proven techniques for producing these assets efficiently as well as examples for each Land class type.

12 Page 12 Here is an example of how the final detail lookup texture compares to the Original and Flattened tile textures. In this example we are looking at one of our Suburban land class tiles. As you can see once you have the flattened texture done, and assuming that any selections or masks remain in separate layers, that the detail lookup texture can be created fairly quickly. 3.4 Blend Masks These are masks used to blend between different types of land class tiles. When two different types of tiles are adjacent, the system automatically overlaps and then blends between the two using these 1024x1024, 1 bit masks. The source art for the masks will be authored as a layer on top of each landclass texture. A PS action is then run to extract the masks and assemble them into their runtime format in which all 8 tiles are stacked vertically in one file, resulting in a file that is 1024 x masks are needed to generate all possible combinations of adjacent tiles. Here are some examples of masks used to blend forest areas together:

13 Page Seasonal Variations Part of what makes the FlightSim and TrainSim worlds so rich is the realistic weather and seasonal changes that are part of the immersive environment. In order to render our terrain with realistic depictions of the seasons we need to create seasonal variations of all of the terrain tiles. For our system we have 5 seasons: 1. Summer (the main tile set which is built in the initial flattening process) 2. Fall 3. Winter (winter terrain without snow) 4. Hard Winter (winter terrain covered with snow) 5. Spring All of our seasonal variations are built off of the Summer tiles set. Here is an example of how a summer tile is turned into a fall tile. Summer and Fall seasonal variations of the same tile To get this fall effect the artist usually uses a combination of layer effects with layer masks helping to limit the effect to specific areas. Below is a shot of the two Photoshop layers that turn the Summer tile on the left into the Fall tile on the right.

14 Page Annotations To complete the process and make the world look like the location that the original aerial imagery depicted before the 3D objects were removed, the game engine will need to place 3D models back into the environment. We have a large library of Scenery Objects including buildings, various manmade objects and vegetation, but in order for the placement of the geometry to lineup with the underling terrain tile those objects will need to be manually aligned to that image. To do this we have an Annotator tool that is designed to let you pick classes of objects and place regions over the image of the tile in the location and, depending on the type of object, the orientation of those 3D models. In the image below (taken from the first version of our annotator) the green boxes you see in the work window represent the object class that you are placing down. The game engine will than place randomly selected variations of that object class into that region.

15 Page Sign-Off Checklist Prior to uploading any Terrain Tile assets to be signed off we would like your team to evaluate the assets for a number of criteria which we have found to be problematic while developing these procedures. We will provide more detailed information about the check points that we would like your team cover in the more in-depth documents that will follow. The check points will cover two general types; those criteria that are required to even be considered for sign-off and those criteria that are more subjective in nature. We expect that your team will gradually become more adept at evaluating the assets for the subjective criteria as we go through the initial rounds of feedback. 4.1 Required For Sign-off Consideration These Criteria will be required to submit the asset for evaluation. These check points will be objective in nature with unambiguous criteria requiring only a present or not present evaluation. These criteria will primarily be procedural in nature such as; Correct file naming Correctly structured Photoshop files with properly labeled layers. Assets that have all the required elements We will provide a clear list of checkpoints to go through prior to uploading the assets. 4.2 Additional Check Points These will be specific visual qualities but will generally be of a subjective nature. These check points should be used to evaluate the assets for meeting or exceeding the visual bar set by our team. We anticipate that your team will quickly get in sync with our expectations in these subjective areas as well; however, these areas will be our primary focus as we get your team familiar with the processes and our expectations. Criteria in this area might include checking for things such as; Color matching between similar tiles or tile sets Making sure that all the tiles that need to match up seamlessly are seamlessly matched. Making sure that similar terrain types match stylistically In our documentation of these criteria we will provide good visual examples of what we are looking for and what visual anomalies will be problematic.