diff --git a/examples/srtm.cpp b/examples/srtm.cpp
index 85de728f..3cdd2459 100644
--- a/examples/srtm.cpp
+++ b/examples/srtm.cpp
@@ -27,8 +27,8 @@
 #include <psemek/util/to_string.hpp>
 #include <psemek/util/moving_average.hpp>
 #include <psemek/util/recursive.hpp>
-#include <psemek/util/threadpool.hpp>
 #include <psemek/util/lru_cache.hpp>
+#include <psemek/async/threadpool.hpp>
 
 #include <fstream>
 #include <iomanip>
@@ -79,6 +79,8 @@ private:
 	T speed_;
 };
 
+static const float exaggeration = 1.f;
+
 struct height_provider
 {
 	float height_at(geom::vector<float, 3> const & v);
@@ -272,8 +274,6 @@ struct node_controller
 
 	std::size_t loader_queue_size() const { return loader_.task_count(); }
 
-	void preload(int max_level);
-
 private:
 	struct node_impl
 		: node
@@ -284,10 +284,8 @@ private:
 		std::unique_ptr<node> children[node_child_count];
 		std::size_t uid;
 
-		std::vector<std::int16_t> height_data;
-		std::atomic<bool> height_data_ready = false;
-		bool height_data_loaded = false;
-		bool height_data_loader_dispatched = false;
+		bool data_ready = false;
+		async::future<std::vector<std::int16_t>> height_data_future;
 
 		bool draw(int level) override;
 		node * child(int id) override;
@@ -304,7 +302,7 @@ private:
 	height_provider height_provider_;
 	node_cache node_cache_;
 
-	util::threadpool loader_{"load", 1};
+	async::threadpool loader_{"load", 1};
 	std::atomic<bool> cancel_ = false;
 
 	std::size_t node_count_ = 0;
@@ -367,40 +365,6 @@ node * node_controller::root(int f)
 	return roots_[f].get();
 }
 
-void node_controller::preload(int)
-{
-	std::string strid;
-	auto visit = util::recursive([this, &strid](auto & self, node * n, int level) -> void
-	{
-		auto nn = static_cast<node_impl *>(n);
-		log::info() << "Loading " << strid << "...";
-		util::clock<> clock;
-		nn->load_heights();
-		while (!nn->height_data_ready)
-			std::this_thread::yield();
-		auto const time = clock.count();
-		log::info() << "Loading " << strid << " done (" << time << "s)";
-
-		if (level + 1 < max_child_level && (time >= 0.05 || level < 5))
-		{
-			std::string old_strid = strid;
-			for (int i = 0; i < node_child_count; ++i)
-			{
-				strid = old_strid + "/" + std::to_string(i);
-				self(n->child(i), level + 1);
-			}
-
-			strid = old_strid;
-		}
-	});
-
-	for (int f = 0; f < 20; ++f)
-	{
-		strid = std::to_string(f);
-		visit(root(f), 0);
-	}
-}
-
 std::unique_ptr<node_controller::node_impl> node_controller::make_node()
 {
 	auto n = std::make_unique<node_controller::node_impl>();
@@ -419,21 +383,20 @@ std::unique_ptr<node_controller::node_impl> node_controller::make_node()
 
 bool node_controller::node_impl::draw(int level)
 {
-	if (!height_data_loaded)
+	if (!data_ready)
 	{
-		if (!height_data_loader_dispatched)
-		{
-			load_heights();
-		}
+		load_heights();
 
-		if (!height_data_ready) return false;
+		if (!height_data_future.ready()) return false;
+
+		auto height_data = std::move(height_data_future.get());
 
 		for (auto h : height_data)
-			height_range |= static_cast<float>(h);
+			height_range |= exaggeration * static_cast<float>(h);
 
 		height_buffer.load(height_data, gl::STATIC_DRAW);
 		height_data.clear();
-		height_data_loaded = true;
+		data_ready = true;
 	}
 
 	array.bind();
@@ -501,19 +464,19 @@ node * node_controller::node_impl::child(int id)
 
 void node_controller::node_impl::load_heights()
 {
-	height_data_loader_dispatched = true;
-	controller->loader_.dispatch([this]{
-		if (controller->cancel_) return;
+	if (height_data_future)
+		return;
+
+	height_data_future = controller->loader_.dispatch(async::auto_cancel, [this]() -> std::vector<std::int16_t> {
+		if (controller->cancel_) return {};
 
 		auto cached = controller->node_cache_.load(uid);
 		if (cached)
 		{
-			height_data = std::move(*cached);
-			height_data_ready = true;
-			return;
+			return std::move(*cached);
 		}
 
-		height_data.assign(((node_size + 2) * (node_size + 1)) / 2, 0);
+		std::vector<std::int16_t> height_data(((node_size + 2) * (node_size + 1)) / 2, 0);
 
 		auto * out = height_data.data();
 
@@ -530,7 +493,7 @@ void node_controller::node_impl::load_heights()
 		{
 			for (int j = 0; j <= i; ++j)
 			{
-				if (controller->cancel_) return;
+				if (controller->cancel_) return {};
 
 				*out++ = static_cast<std::int16_t>(controller->height_provider_.height_at(at(i, j)));
 			}
@@ -538,7 +501,7 @@ void node_controller::node_impl::load_heights()
 
 		controller->node_cache_.store(uid, height_data);
 
-		height_data_ready = true;
+		return height_data;
 	});
 }
 
@@ -546,6 +509,7 @@ static char const tile_vs[] =
 R"(#version 330
 
 uniform mat4 u_transform;
+uniform float u_exaggeration;
 
 uniform int u_N;
 uniform vec3 u_p0;
@@ -571,7 +535,7 @@ void main()
 	float t1 = float(j) / float(u_N);
 	float t2 = 1.0 - t0 - t1;
 
-	vec3 p = normalize(u_p0 * t0 + u_p1 * t1 + u_p2 * t2) * (1.0 + in_height / 6400000.0);
+	vec3 p = normalize(u_p0 * t0 + u_p1 * t1 + u_p2 * t2) * (1.0 + u_exaggeration * in_height / 6400000.0);
 	pos = p;
 	gl_Position = u_transform * vec4(p, 1.0);
 	float C = 1.0;
@@ -721,8 +685,6 @@ srtm_app::srtm_app()
 		color_map_neg.clamp();
 		color_map_neg.linear_filter();
 	}
-
-//	nodes.preload(6);
 }
 
 void srtm_app::on_resize(int width, int height)
@@ -858,6 +820,7 @@ void srtm_app::present()
 
 	tile_close_program.bind();
 	tile_close_program["u_transform"] = camera_transform;
+	tile_close_program["u_exaggeration"] = exaggeration;
 	tile_close_program["u_N"] = static_cast<int>(node_size);
 	tile_close_program["u_light"] = light;
 	tile_close_program["u_colormap"] = 0;
@@ -865,6 +828,7 @@ void srtm_app::present()
 	tile_close_program["u_far"] = camera.far_clip;
 	tile_far_program.bind();
 	tile_far_program["u_transform"] = camera_transform;
+	tile_far_program["u_exaggeration"] = exaggeration;
 	tile_far_program["u_N"] = static_cast<int>(node_size);
 	tile_far_program["u_light"] = light;
 	tile_far_program["u_colormap"] = 0;