diff --git a/Cargo.lock b/Cargo.lock
index e3cb4c7..ea395f3 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -5131,6 +5131,17 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "serde_repr"
+version = "0.1.20"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "175ee3e80ae9982737ca543e96133087cbd9a485eecc3bc4de9c1a37b47ea59c"
+dependencies = [
+ "proc-macro2",
+ "quote",
+ "syn 2.0.101",
+]
+
 [[package]]
 name = "serde_spanned"
 version = "0.6.8"
@@ -5721,6 +5732,7 @@ dependencies = [
  "nannou_laser",
  "serde",
  "serde_json",
+ "serde_repr",
  "zmq",
 ]
 
diff --git a/Cargo.toml b/Cargo.toml
index cd73534..e8756a5 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -16,6 +16,7 @@ zmq = "0.10.0"
 
 nannou = "0.19.0"
 nannou_egui = { version = "0.19.0", features = ["wayland"] }
+serde_repr = "0.1.20"
 
 
 [dev-dependencies]
diff --git a/src/bin/render_lines_gui.rs b/src/bin/render_lines_gui.rs
index 777000a..0e22515 100644
--- a/src/bin/render_lines_gui.rs
+++ b/src/bin/render_lines_gui.rs
@@ -3,12 +3,14 @@
 //! UI.
 
 use bevy::math::Mat3;
+use bevy_nannou::prelude::DARK_GRAY;
 use nannou::lyon::geom::euclid::Transform2D;
 use nannou::{geom::Rect, math::map_range as nannou_map_range};
 use nannou::prelude::*;
 use nannou_egui::{self, egui, Egui};
 use nannou_laser::{self as laser, util::map_range};
 use serde_json::Result;
+use trap_rust::trap::tracks::CoordinateSpace;
 use trap_rust::trap::{laser::{apply_homography_matrix, python_cv_h_into_mat3, LaserModel, TMP_PYTHON_LASER_H}, tracks::{LaserPoints, RenderableLines}};
 use zmq::Socket;
 use std::sync::{mpsc, Arc};
@@ -37,6 +39,7 @@ struct Model {
     last_update: Instant,
     // dimming_factor: f32,
     lost_alpha: f32,
+    connected: bool,
 }
 
 struct LaserSettings {
@@ -103,6 +106,7 @@ fn zmq_receive(model: &mut Model) {
         // let msg: Frame = serde_json::from_str(&json[4..]).expect("No valid json?");
         let res: Result<RenderableLines> = serde_json::from_str(&json);
         model.lost_alpha = 1.;
+        model.connected = true;
 
         lines = match res {
             Ok(lines) => lines, // if Ok(255), set x to 255
@@ -110,13 +114,13 @@ fn zmq_receive(model: &mut Model) {
                 println!("No valid json?");
                 println!("{}", _e);
                 // empty if invalid
-                RenderableLines{
-                    lines: Vec::new()
-                }
+                RenderableLines::new()
             }, // if Err("some message"), panic with error message "some message"
         };
     } else if model.last_update < Instant::now() - Duration::from_millis(100){
         // set lines empty, if no new input for > 100ms (10fps)
+        model.connected = false;
+
         if model.lost_alpha > 0.{
 
             println!("No input, clear lines!!");
@@ -126,9 +130,7 @@ fn zmq_receive(model: &mut Model) {
             }
             lines = model.current_lines.with_alpha(model.lost_alpha);
         } else {   
-            lines = RenderableLines{
-                lines: Vec::new()
-            }
+            lines = RenderableLines::new()
         }
     } else {
         // No new lines, break
@@ -241,6 +243,7 @@ fn model(app: &App) -> Model {
         current_lines: current_lines,
         last_update: Instant::now(),
         lost_alpha: 1.,
+        connected: true,
         // dimming_factor: 1.,
     }
 }
@@ -265,12 +268,19 @@ const LASER_H: Mat3 = python_cv_h_into_mat3(TMP_PYTHON_LASER_H);
 fn laser_frame_producer(model: &mut LaserModel, frame: &mut laser::Frame){
     
     let points: LaserPoints = (&model.current_lines).into();
+    let space = &model.current_lines.space;
     let pointno = points.len();
 
     let mut new_points = Vec::new();
     for point in points.into_iter() {
         let p = point.position;
-        let new_position = apply_homography_matrix(LASER_H, &p);
+        let new_position = match space {
+            CoordinateSpace::World => apply_homography_matrix(LASER_H, &p),  
+            CoordinateSpace::Laser => p,
+            _ => panic!("Invalid coordinate space"),
+            
+        };
+        // let new_position = apply_homography_matrix(LASER_H, &p);
         // let s = 1.;  // when using TMP_PYTHON_LASER_H_FOR_NANNOU -- doesn't work?
         let s = 0xFFF as f32 / 2.; // when using TMP_PYTHON_LASER_H
         let position = [new_position[0]/s - 1., new_position[1]/s - 1.];
@@ -514,7 +524,15 @@ fn view_line_canvas(app: &App, model: &Model, frame: Frame) {
     let draw = app.draw();
 
     // set background to blue
-    draw.background().color(DARKGRAY);
+    
+    let bgcolor = match model.current_lines.space {
+        CoordinateSpace::Laser => MEDIUMSLATEBLUE,
+        _ => match model.connected{
+            true => DARKGRAY,
+            false => LIGHTCORAL,
+        },
+    };
+    draw.background().color(bgcolor);
 
     let win = app.window_rect();
 
@@ -522,6 +540,8 @@ fn view_line_canvas(app: &App, model: &Model, frame: Frame) {
     let translate_x = -300.;
     let translate_y = -100.;
 
+    
+
     draw_grid(&draw, &win, scale, 1.);
     // let t = app.time;
     
diff --git a/src/trap/tracks.rs b/src/trap/tracks.rs
index 10ec466..c253856 100644
--- a/src/trap/tracks.rs
+++ b/src/trap/tracks.rs
@@ -2,7 +2,7 @@ use bevy::prelude::*;
 use serde::{Serialize,Deserialize};
 use std::time::Instant;
 use nannou_laser as laser;
-
+use serde_repr::*;
 
 #[derive(Serialize,Deserialize)]
 pub struct Frame {
@@ -67,14 +67,25 @@ impl RenderableLine {
     }
 }
 
+// see also trap/lines.py for matching values
+#[derive(Clone, Debug, Serialize_repr, Deserialize_repr)]
+#[repr(u8)]
+pub enum CoordinateSpace {
+    Image = 1,
+    UndistortedImage = 2,
+    World = 3,
+    Laser = 4,
+}
+
 #[derive(Clone, Debug, Serialize, Deserialize)]
 pub struct RenderableLines{
-    pub lines: Vec<RenderableLine>
+    pub lines: Vec<RenderableLine>,
+    pub space: CoordinateSpace, // enum in python
 }
 
 impl RenderableLines{
     pub fn new() -> Self{
-        RenderableLines { lines: Vec::new() }
+        RenderableLines { lines: Vec::new(), space: CoordinateSpace::World }
     }
 
     // pub fn append(&mut self, &mut rl: RenderableLines){
@@ -93,7 +104,7 @@ impl RenderableLines{
             return self.clone();
         }
 
-        Self { lines: self.lines.iter().map(|l| { l.with_alpha(alpha)}).collect() }
+        Self { lines: self.lines.iter().map(|l| { l.with_alpha(alpha)}).collect(), space: self.space.clone() }
     }
 
 }
@@ -124,7 +135,7 @@ impl From<&Track> for RenderableLines{
             }
             lines.push(RenderableLine{points})
         }
-        RenderableLines { lines }
+        RenderableLines { lines, space: CoordinateSpace::World }
     }
 }
 
diff --git a/src/trap/zmqplugin.rs b/src/trap/zmqplugin.rs
index adfa4b1..93e056b 100644
--- a/src/trap/zmqplugin.rs
+++ b/src/trap/zmqplugin.rs
@@ -57,6 +57,7 @@ fn receive_zmq_lines(
     if items[0].is_readable() {
         let json = subscriber.recv_string(0).unwrap().unwrap();
         // dbg!(&json[4..]);
+        dbg!(&json);
 
         // let msg: Frame = serde_json::from_str(&json[4..]).expect("No valid json?");
         let res: Result<RenderableLines> = serde_json::from_str(&json);