370 lines
12 KiB
C++
370 lines
12 KiB
C++
// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
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/*
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This program is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <AP_HAL.h>
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#include <AP_Common.h>
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#include <AP_Math.h>
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#include <GCS_MAVLink.h>
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#include <GCS.h>
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#include "AP_Terrain.h"
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#include <assert.h>
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#include <stdio.h>
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#if HAVE_AP_TERRAIN
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#define TERRAIN_DEBUG 0
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extern const AP_HAL::HAL& hal;
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// table of user settable parameters
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const AP_Param::GroupInfo AP_Terrain::var_info[] PROGMEM = {
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// @Param: ENABLE
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// @DisplayName: Terrain following enable
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// @Description: enable terrain following
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// @Values: 0:Disable,1:Enable
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AP_GROUPINFO("ENABLE", 0, AP_Terrain, enable, 0),
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// @Param: SPACING
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// @DisplayName: Terrain grid spacing
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// @Description: distance between terrain grid points in meters
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// @Units: meters
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// @Increment: 1
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AP_GROUPINFO("SPACING", 1, AP_Terrain, grid_spacing, 100),
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AP_GROUPEND
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};
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// constructor
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AP_Terrain::AP_Terrain(AP_AHRS &_ahrs) :
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ahrs(_ahrs),
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last_request_time_ms(0)
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{
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AP_Param::setup_object_defaults(this, var_info);
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}
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#if TERRAIN_DEBUG
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#define ASSERT_RANGE(v,minv,maxv) assert((v)<=(maxv)&&(v)>=(minv))
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#else
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#define ASSERT_RANGE(v,minv,maxv)
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#endif
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/*
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calculate bit number in grid_block bitmap. This corresponds to a
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bit representing a 4x4 mavlink transmitted block
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*/
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uint8_t AP_Terrain::grid_bitnum(uint8_t idx_x, uint8_t idx_y)
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{
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ASSERT_RANGE(idx_x,0,27);
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ASSERT_RANGE(idx_y,0,31);
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uint8_t subgrid_x = idx_x / TERRAIN_GRID_MAVLINK_SIZE;
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uint8_t subgrid_y = idx_y / TERRAIN_GRID_MAVLINK_SIZE;
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ASSERT_RANGE(subgrid_x,0,TERRAIN_GRID_BLOCK_MUL_X-1);
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ASSERT_RANGE(subgrid_y,0,TERRAIN_GRID_BLOCK_MUL_Y-1);
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return subgrid_y + TERRAIN_GRID_BLOCK_MUL_Y*subgrid_x;
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}
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/*
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given a grid_info check that a given idx_x/idx_y is available (set
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in the bitmap)
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*/
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bool AP_Terrain::check_bitmap(const struct grid_block &grid, uint8_t idx_x, uint8_t idx_y)
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{
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uint8_t bitnum = grid_bitnum(idx_x, idx_y);
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return (grid.bitmap & (((uint64_t)1U)<<bitnum)) != 0;
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}
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/*
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given a location, calculate the 32x28 grid SW corner, plus the
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grid indices
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*/
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void AP_Terrain::calculate_grid_info(const Location &loc, struct grid_info &info) const
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{
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// grids start on integer degrees. This makes storing terrain data
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// on the SD card a bit easier
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info.lat_degrees = (loc.lat<0?(loc.lat-9999999L):loc.lat) / (10*1000*1000L);
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info.lon_degrees = (loc.lng<0?(loc.lng-9999999L):loc.lng) / (10*1000*1000L);
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// create reference position for this rounded degree position
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Location ref;
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ref.lat = info.lat_degrees*10*1000*1000L;
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ref.lng = info.lon_degrees*10*1000*1000L;
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// find offset from reference
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Vector2f offset = location_diff(ref, loc);
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// get indices in terms of grid_spacing elements
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uint32_t idx_x = offset.x / grid_spacing;
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uint32_t idx_y = offset.y / grid_spacing;
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// find indexes into 32*28 grids for this degree reference. Note
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// the use of TERRAIN_GRID_BLOCK_SPACING_{X,Y} which gives a one square
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// overlap between grids
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uint16_t grid_idx_x = idx_x / TERRAIN_GRID_BLOCK_SPACING_X;
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uint16_t grid_idx_y = idx_y / TERRAIN_GRID_BLOCK_SPACING_Y;
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// find the indices within the 32*28 grid
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info.idx_x = idx_x % TERRAIN_GRID_BLOCK_SPACING_X;
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info.idx_y = idx_y % TERRAIN_GRID_BLOCK_SPACING_Y;
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// find the fraction (0..1) within the square
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info.frac_x = (offset.x - idx_x * grid_spacing) / grid_spacing;
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info.frac_y = (offset.y - idx_y * grid_spacing) / grid_spacing;
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// calculate lat/lon of SW corner of 32*28 grid_block
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location_offset(ref,
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grid_idx_x * TERRAIN_GRID_BLOCK_SPACING_X * (float)grid_spacing,
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grid_idx_y * TERRAIN_GRID_BLOCK_SPACING_Y * (float)grid_spacing);
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info.grid_lat = ref.lat;
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info.grid_lon = ref.lng;
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ASSERT_RANGE(info.idx_x,0,TERRAIN_GRID_BLOCK_SPACING_X-1);
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ASSERT_RANGE(info.idx_y,0,TERRAIN_GRID_BLOCK_SPACING_Y-1);
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ASSERT_RANGE(info.frac_x,0,1);
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ASSERT_RANGE(info.frac_y,0,1);
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}
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/*
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find a grid structure given a grid_info
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*/
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AP_Terrain::grid_cache &AP_Terrain::find_grid(const struct grid_info &info)
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{
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uint16_t oldest_i = 0;
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// see if we have that grid
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for (uint16_t i=0; i<TERRAIN_GRID_BLOCK_CACHE_SIZE; i++) {
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if (cache[i].grid.lat == info.grid_lat &&
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cache[i].grid.lon == info.grid_lon) {
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cache[i].last_access_ms = hal.scheduler->millis();
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return cache[i];
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}
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if (cache[i].last_access_ms < cache[oldest_i].last_access_ms) {
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oldest_i = i;
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}
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}
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// Not found. Use the oldest grid and make it this grid,
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// initially unpopulated
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struct grid_cache &grid = cache[oldest_i];
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memset(&grid, 0, sizeof(grid));
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grid.grid.lat = info.grid_lat;
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grid.grid.lon = info.grid_lon;
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grid.grid.spacing = grid_spacing;
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grid.last_access_ms = hal.scheduler->millis();
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return grid;
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}
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/*
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return terrain height in meters above average sea level (WGS84) for
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a given position
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*/
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bool AP_Terrain::height_amsl(const Location &loc, float &height)
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{
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if (!enable) {
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return false;
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}
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struct grid_info info;
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calculate_grid_info(loc, info);
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// find the grid
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const struct grid_block &grid = find_grid(info).grid;
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/*
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note that we rely on the one square overlap to ensure these
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calculations don't go past the end of the arrays
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*/
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ASSERT_RANGE(info.idx_x, 0, TERRAIN_GRID_BLOCK_SIZE_X-2);
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ASSERT_RANGE(info.idx_y, 0, TERRAIN_GRID_BLOCK_SIZE_Y-2);
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// check we have all 4 required heights
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if (!check_bitmap(grid, info.idx_x, info.idx_y) ||
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!check_bitmap(grid, info.idx_x, info.idx_y+1) ||
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!check_bitmap(grid, info.idx_x+1, info.idx_y) ||
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!check_bitmap(grid, info.idx_x+1, info.idx_y+1)) {
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return false;
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}
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// hXY are the heights of the 4 surrounding grid points
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int16_t h00, h01, h10, h11;
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h00 = grid.height[info.idx_x+0][info.idx_y+0];
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h01 = grid.height[info.idx_x+0][info.idx_y+1];
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h10 = grid.height[info.idx_x+1][info.idx_y+0];
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h11 = grid.height[info.idx_x+1][info.idx_y+1];
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float avg1 = (1.0f-info.frac_x) * h00 + info.frac_x * h10;
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float avg2 = (1.0f-info.frac_x) * h01 + info.frac_x * h11;
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float avg = (1.0f-info.frac_y) * avg1 + info.frac_y * avg2;
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height = avg;
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return true;
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}
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/*
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request any missing 4x4 grids from a block
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*/
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bool AP_Terrain::request_missing(mavlink_channel_t chan, const struct grid_info &info)
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{
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// find the grid
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struct grid_block &grid = find_grid(info).grid;
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// see if it is fully populated
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if ((grid.bitmap & bitmap_mask) == bitmap_mask) {
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// it is fully populated, nothing to do
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return false;
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}
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/*
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ask the GCS to send a set of 4x4 grids
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*/
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mavlink_msg_terrain_request_send(chan, grid.lat, grid.lon, grid_spacing, bitmap_mask & ~grid.bitmap);
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last_request_time_ms = hal.scheduler->millis();
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return true;
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}
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/*
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send any pending terrain request to the GCS
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*/
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void AP_Terrain::send_request(mavlink_channel_t chan)
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{
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if (enable == 0) {
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// not enabled
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return;
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}
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// did we request recently?
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if (hal.scheduler->millis() - last_request_time_ms < 2000) {
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// too soon to request again
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return;
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}
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Location loc;
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if (!ahrs.get_position(loc)) {
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// we don't know where we are
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return;
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}
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// request any missing 4x4 blocks in the current grid
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struct grid_info info;
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calculate_grid_info(loc, info);
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if (request_missing(chan, info)) {
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return;
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}
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// also request a larger set of up to 9 grids
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for (int8_t x=-1; x<=1; x++) {
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for (int8_t y=-1; y<=1; y++) {
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Location loc2 = loc;
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location_offset(loc2,
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x*TERRAIN_GRID_BLOCK_SIZE_X*0.7f*grid_spacing,
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y*TERRAIN_GRID_BLOCK_SIZE_Y*0.7f*grid_spacing);
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struct grid_info info2;
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calculate_grid_info(loc2, info2);
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if (request_missing(chan, info2)) {
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return;
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}
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}
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}
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// request the current loc last to ensure it has highest last
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// access time
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if (request_missing(chan, info)) {
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return;
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}
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}
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/*
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handle terrain data from GCS
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*/
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void AP_Terrain::handle_data(mavlink_message_t *msg)
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{
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mavlink_terrain_data_t packet;
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mavlink_msg_terrain_data_decode(msg, &packet);
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uint16_t i;
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for (i=0; i<TERRAIN_GRID_BLOCK_CACHE_SIZE; i++) {
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if (cache[i].grid.lat == packet.lat &&
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cache[i].grid.lon == packet.lon &&
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cache[i].grid.spacing == packet.grid_spacing &&
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packet.gridbit < 56) {
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break;
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}
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}
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if (i == TERRAIN_GRID_BLOCK_CACHE_SIZE) {
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// we don't have that grid, ignore data
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return;
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}
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struct grid_cache &gcache = cache[i];
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struct grid_block &grid = gcache.grid;
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uint8_t idx_x = (packet.gridbit / TERRAIN_GRID_BLOCK_MUL_Y) * TERRAIN_GRID_MAVLINK_SIZE;
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uint8_t idx_y = (packet.gridbit % TERRAIN_GRID_BLOCK_MUL_Y) * TERRAIN_GRID_MAVLINK_SIZE;
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ASSERT_RANGE(idx_x,0,(TERRAIN_GRID_BLOCK_MUL_X-1)*TERRAIN_GRID_MAVLINK_SIZE);
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ASSERT_RANGE(idx_y,0,(TERRAIN_GRID_BLOCK_MUL_Y-1)*TERRAIN_GRID_MAVLINK_SIZE);
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for (uint8_t x=0; x<TERRAIN_GRID_MAVLINK_SIZE; x++) {
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for (uint8_t y=0; y<TERRAIN_GRID_MAVLINK_SIZE; y++) {
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grid.height[idx_x+x][idx_y+y] = packet.data[x*TERRAIN_GRID_MAVLINK_SIZE+y];
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ASSERT_RANGE(grid.height[idx_x+x][idx_y+y], 1, 20000);
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}
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}
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gcache.grid.bitmap |= ((uint64_t)1) << packet.gridbit;
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#if TERRAIN_DEBUG
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hal.console->printf("Filled bit %u idx_x=%u idx_y=%u\n",
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(unsigned)packet.gridbit, (unsigned)idx_x, (unsigned)idx_y);
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if (gcache.grid.bitmap == bitmap_mask) {
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hal.console->printf("--lat=%12.7f --lon=%12.7f %u\n",
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grid.lat*1.0e-7f,
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grid.lon*1.0e-7f,
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grid.height[0][0]);
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Location loc2;
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loc2.lat = grid.lat;
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loc2.lng = grid.lon;
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location_offset(loc2, 28*grid_spacing, 32*grid_spacing);
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hal.console->printf("--lat=%12.7f --lon=%12.7f %u\n",
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loc2.lat*1.0e-7f,
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loc2.lng*1.0e-7f,
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grid.height[27][31]);
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}
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#endif
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}
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/*
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update terrain data. Check if we need to request more grids. This
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should be called at 1Hz
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*/
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void AP_Terrain::update(void)
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{
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Location loc;
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if (!ahrs.get_position(loc)) {
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// we don't know where we are
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return;
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}
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#if TERRAIN_DEBUG
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float height;
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if (height_amsl(loc, height)) {
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printf("height %.2f\n", height);
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}
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#endif
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}
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#endif // HAVE_AP_TERRAIN
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