Maps Renderer

Note

SW Release Applicability: This tutorial is applicable to modules in NVIDIA DRIVE Software releases.

The Maps Renderer

• renders map data contained in the NVIDIA^® DriveWorks Maps module
• renders objects defined in WGS84 coordinates on top of the map

It uses the Render Engine to render the data.

General Usage

// init map

// init maps renderer module
dwMapsRenderer_initialize(...);

while (...)
{
    //
    // orthographic top down rendering
    //

    // select render engine tile
    dwRenderEngine_setTile(...)

    // setup camera for top down view onto map data
    dwMapsRenderer_setTopDownProjection(...); // camera zoom
    dwMapsRenderer_setTopDownModelView(...);  // camera position

    // render
    dwMapsRenderer_renderMap(...)
    dwMapsRenderer_renderLanePlan(...)
    dwMapsRenderer_renderPolylines(...)
    dwMapsRenderer_renderOrientedBox(...)
    dwMapsRenderer_renderBox(...)



    //
    // perspective rendering
    //

    // select render engine tile
    dwRenderEngine_setTile(...)

    // set camera zoom
    dwRenderEngine_setPerspectiveProjection(...)

    // set camera position and orientation
    dwMapsRenderer_setLookAt(...)

    // render
    dwMapsRenderer_renderMap(...)
    dwMapsRenderer_renderLanePlan(...)
    dwMapsRenderer_renderPolylines(...)
    dwMapsRenderer_renderOrientedBox(...)
    dwMapsRenderer_renderBox(...)
}

// release module
dwMapsRenderer_release(...);

Initialization

The Maps Renderer is initialized with a map handle of the DriveWorks Maps module and initializes a render buffer using the Render Engine. That render buffer gets filled with lines for all lane dividers in the map. Additionally, a buffer gets allocated for additional renderings during runtime. The user has to specify the maximum number of lines that will be needed during one of the render calls that render additional data (all render calls other than dwMapsRenderer_renderMap()). Also, it can be chosen whether the line directions of the map should be visible, so that it can be seen where lines start and end. When setting showMapLineDirections to true, the lines will be shaded (darker to brighter) to show the line directions.

dwStatus dwMapsRenderer_initialize(dwMapsRendererHandle_t* mapsRenderer,
                                   uint32_t maxRenderBufferLineCount,
                                   uint32_t maxRenderBufferPointCount,
                                   bool showMapLineDirections,
                                   dwRenderEngineHandle_t renderEngine,
                                   dwConstMapHandle_t map);

dwRenderEngine

The Maps Renderer uses the Render Engine. It renders any lines with the current setting of the Render Engine. That means, it renders into the active tile, using its projection and modelView matrix and with line width settings. Color handling is different depending on the render call. There are helper functions to set up the projection and modelView matrices for the Maps Renderer.

Render Functions

The Maps Renderer provides the following render functions:

dwMapsRenderer_renderMap

Renders all map lane dividers.

dwMapsRenderer_renderLanePlan

Render the lines of a lane plan from the DriveWorks Lane Planner module.

dwMapsRenderer_renderGeoPolylines

Render a list of polylines of WGS84 points.

dwMapsRenderer_renderOrientedGeoBox

Render an oriented box, defined by a WGS84 point, a bearing (clockwise angle to north) in radian, length and width in meters, optionally with a center cross and/or an arrow towards the bearing direction.

dwMapsRenderer_renderGeoBox

Render an axis-aligned square box defined by a WGS84 point and a size in meters, optionally with a center cross.

Camera setup

There are helper functions to set up projection and modelview matrices.

dwMapsRenderer_setTopDownProjection

Set the projection matrix in the renderEngine tile such that the active tile height covers a given distance of map data in meters.

dwMapsRenderer_setTopDownModelView

Set the modelView matrix in the renderEngine tile such that the given WGS84 coordinate is in the tile center.

dwMapsRenderer_moveTopDownModelView

Move the modelView matrix by a given delta in meters. This assumes the current modelView matrix is already set up for top-down orthographic view.

dwMapsRenderer_setLookAt

Set up the modelView matrix such that the camera is at a given WGS84 point, looking towards another WGS84 point.

Pixel Queries

There are helper functions to check whether a screen pixel is within a box that is defined by WGS84 coordinates:

dwMapsRenderer_isPixelCoordInOrientedBox
dwMapsRenderer_isPixelCoordInBox

Coordinate Queries

There are helper functions to transform between different coordinates.

dwMapsRenderer_getRenderCoord

Returns the internally used render coordinate of a WGS84 point. This can be used to externally render lines into the same coordinate system.

dwMapsRenderer_getWGS84CoordFromRenderCoord

Returns the WGS84 coordinate for a point given in the internal render coordinate system.

dwMapsRenderer_getWGS84Coord

Returns the WGS84 coordinate that corresponds to a screen pixel. This can be used to localize mouse clicks on the screen, for example.

dwMapsRenderer_getWGS84CoordNDC

Returns the WGS84 coordinate that corresponds to a Normalized Display Coordinate system, with (0,0) in the center of the screen, going from (-1,-1) to (1,1). This can be helpful when selecting a point at a given position on the screen, e.g. screen center.

For more information see Map Access Sample .