Water Bodies - Advanced Workflow

This article outlines the steps involved in building a 3D model with accurate water bodies, including tips and pointers for achieving optimum results. The process involves five main steps:

1. Build the project to generate a preliminary 3DML
2. Create the water body polygons and adjust their positions
3. Build the project to generate textured tiles
4. Retouch the water bodies
5. Build the final 3DML

See Work with Water Bodies for an introduction to water body polygons.

Step 1: Run an initial build

Run an initial build of the project before adding the water bodies (Home tab > Build > Select Complete Project). The 3DML generated will be used to place the water polygons at the correct elevation.  More about: Building a project >

Step 2: Draw water body polygons in the correct areas using the generated 3DML 

1. Navigate to the location of the water body, and on the Home tab > Retouch > select Create Leveled Water Body. More about: Working with water body polygons >
   Note:  Use leveled water bodies for most lakes, seas, reservoirs, ponds, etc.
2. Zoom in to the 3DML to add the first point of the polygon. The polygon's first point determines the elevation of the water polygon, so it is important to place it with maximum accuracy. Make sure you place the polygon points on the 3DML and not on the terrain below. 
   The first polygon point placed on the bank of the pond:
3. Click again to add additional points of the polygon until you have marked the entire shape. You can zoom out and add the rest of the water polygon points from any zoom level since the water elevation for all polygon points is determined by your first point. Right-click to finish drawing the water polygon. 
   The newly created leveled water polygon: 
   
   Vertices view: 
4. Verify the accuracy of the water polygon's elevation by querying the elevation of the water body (Tools tab > Query) and making sure it's value is nearly the same as that of the polygon (Check the polygon's elevation in the Water Polygon List). Edit the position of the polygon points, if necessary. More about: Editing water polygons >
   Note:  It is recommended to check at least two or three different points around the water body to ensure it wasn't placed too high or too low or missed snapping to any vertex. If the water polygon is on the edge of the project, it is recommended to extend the water polygon 5-10% outside the reconstruction area to ensure that no artifacts are created on the polygon's edges.  

Step 3: Rebuild the tiles that intersect with the water polygon

1. Home tab > Build. Select Custom steps: from Auto to Texture, or from Auto to Output. PhotoMesh will automatically identify the water tiles that intersect with the water polygon and rebuild them from the point cloud stage. When rebuilding, you can lower the point cloud resolution (on Reconstruction tab) and the mesh resolution (on the Reconstruction tab), by a factor of one. For example, if in your initial project settings, you set Point Cloud Resolution to 1/2 and Mesh Resolution to Full, then for your water tiles, you should select: Point Cloud Resolution - 1/4, Mesh Resolution - Medium, Smooth Surfaces (set on the Reconstruction tab) - No. More about: Rebuilding a project >
   Note:  If you want to select the water tiles manually, open the Water Polygon list, right-click the newly created water polygon, and select Select Tiles. 

Step 4: Review the newly created water tiles, and retouch as required

The generated water tiles may have either floating artifacts or non-homogeneous texture. See the steps below on how to fix both these issues.

• Floating Artifacts: This may result from foam, water vegetation, or a color variation in some parts of the water body:
  1. Home tab > Retouch > Open Manual Retouch Toolbox > Remove Floating or Flatten Polygon.
  2. Rebuild the affected tiles (Home tab > Build >Custom >Select from Auto to Texture). PhotoMesh identifies which tiles require rebuilding.
  3. Note that the floating artifacts were removed from the retouched tiles:
• Non-Homogeneous Texture: This can result from the texturing of each tile from different photos.
  1. Lower the point cloud resolution to 1/4 (Home tab > click Build > in Build Parameters dialog > Reconstruction tab > set Point Cloud Quality to 1/4).
  2. On the Reconstruction tab, set Point Cloud Min. Number of Matches to 4.
  3. Add the Reconstruction Flag: dpc_mgi 0. 
  4. Alternatively, you can use manual retouch tools to set a single, custom color that replaces the texturing in all the photos (Home tab > Retouch > Open Manual Retouch Toolbox > Remove Floating or Flatten Polygon > select Single Color Fill > select the color to use.

More about: Retouching a mesh layer >

Step 5:

Build the final mesh model (Home tab > Build > Custom >Select from Auto to Project Output. PhotoMesh automatically identifies the tiles that require rebuilding. The output should look as follows:Example of the final 3DML:

More about: Setting build parameters >