String gridCellSzStr = String.format(Locale.US, "%.12f,%.12f", sampleGrid.getCellSize().y,
sampleGrid.getCellSize().x);
String offRoadDistStr = String.format(Locale.US, "%f",
sampleGridRenderer.getOffRoadDistanceMeters(precisionMeters));
PngChunkTEXT gridCornerChunk = new PngChunkTEXT(imgInfo);
gridCornerChunk.setKeyVal(OTPA_GRID_CORNER, gridCornerStr);
pw.getChunksList().queue(gridCornerChunk);
PngChunkTEXT gridCellSzChunk = new PngChunkTEXT(imgInfo);
gridCellSzChunk.setKeyVal(OTPA_GRID_CELL_SIZE, gridCellSzStr);
pw.getChunksList().queue(gridCellSzChunk);
PngChunkTEXT offRoadDistChunk = new PngChunkTEXT(imgInfo);
offRoadDistChunk.setKeyVal(OTPA_OFFROAD_DIST, offRoadDistStr);
pw.getChunksList().queue(offRoadDistChunk);
double unit;
switch (zDataType) {
case TIME: