Implemented following the previous segments and the elevations to flat

ground

src/main/java/com/elphel/imagej/common/FilterProperties.java

+package com.elphel.imagej.common;
+
+import java.util.Properties;
+import java.util.Set;
+
+public class FilterProperties {
+	public static Properties keep(
+			Properties  properies,
+			Set<String> keys) {
+		Properties filtered_properties = new Properties();
+		for (String key:keys) {
+			if (properies.getProperty(key) != null) {
+			filtered_properties.setProperty(key, properies.getProperty(key));
+			}
+		}
+		return filtered_properties;
+	}
+	public static Properties remove(
+			Properties  properies,
+			Set<String> keys) {
+		Properties filtered_properties = new Properties();
+		for (String key:properies.stringPropertyNames()) {
+			if (!keys.contains(key)) {
+				filtered_properties.setProperty(key, properies.getProperty(key));
+			}
+		}
+		return filtered_properties;
+	}
+
+}

src/main/java/com/elphel/imagej/mcp/McpServer.java

@@ -61,6 +61,7 @@ public class McpServer {
         server.createContext("/mcp/fs/head", new FsHeadHandler());
         server.createContext("/mcp/fs/tail", new FsTailHandler());
         server.createContext("/mcp/fs/glob", new FsGlobHandler());
+        server.createContext("/mcp/fs/csvcol", new FsCsvColHandler());
         server.setExecutor(null);
         server.start();
         if (Eyesis_Correction.MCP_DEBUG_LEVEL >= Eyesis_Correction.MINIMAL_DEBUG_MCP) {
@@ -188,11 +189,17 @@ public class McpServer {
             List<java.nio.file.Path> roots = McpFsAccess.getAllowedRoots();
             StringBuilder sb = new StringBuilder();
             sb.append("{\"ok\":true,\"roots\":[");
+            int outIndex = 0;
             for (int i = 0; i < roots.size(); i++) {
-                if (i > 0) {
+                java.nio.file.Path root = roots.get(i);
+                if (!java.nio.file.Files.isDirectory(root)) {
+                    continue;
+                }
+                if (outIndex > 0) {
                     sb.append(",");
                 }
-                sb.append("\"").append(jsonEscape(roots.get(i).toString())).append("\"");
+                sb.append("\"").append(jsonEscape(root.toString())).append("\"");
+                outIndex++;
             }
             sb.append("]}");
             sendJson(exchange, 200, sb.toString());
@@ -425,6 +432,70 @@ public class McpServer {
         }
     }
 
+    // codex 2026-01-28: read a single column from a delimited text file (1-based column index)
+    private class FsCsvColHandler implements HttpHandler {
+        @Override
+        public void handle(HttpExchange exchange) throws IOException {
+            Map<String, String> params = parseParams(exchange);
+            String pathStr = params.get("path");
+            String colStr = params.get("col");
+            if (pathStr == null || colStr == null) {
+                sendJson(exchange, 400, "{\"ok\":false,\"error\":\"Missing path or col\"}");
+                return;
+            }
+            int col = parseInt(colStr, -1);
+            if (col < 1) {
+                sendJson(exchange, 400, "{\"ok\":false,\"error\":\"Column index must be >= 1\"}");
+                return;
+            }
+            java.nio.file.Path path = McpFsAccess.normalizePath(pathStr);
+            if (path == null || !McpFsAccess.isAllowed(path)) {
+                sendJson(exchange, 403, "{\"ok\":false,\"error\":\"Path not allowed\"}");
+                return;
+            }
+            if (!java.nio.file.Files.isRegularFile(path)) {
+                sendJson(exchange, 400, "{\"ok\":false,\"error\":\"Not a file\"}");
+                return;
+            }
+            String sep = params.get("sep");
+            String delim = "\t";
+            if (sep != null && !sep.isEmpty()) {
+                if ("\\t".equals(sep) || "tab".equalsIgnoreCase(sep)) {
+                    delim = "\t";
+                } else {
+                    delim = sep;
+                }
+            }
+            int max = parseInt(params.get("max"), 100000);
+            if (max < 1) {
+                max = 1;
+            }
+            String splitRegex = java.util.regex.Pattern.quote(delim);
+            List<String> values = new ArrayList<String>();
+            try (java.io.BufferedReader reader = java.nio.file.Files.newBufferedReader(path, StandardCharsets.UTF_8)) {
+                String line;
+                while ((line = reader.readLine()) != null) {
+                    String[] parts = line.split(splitRegex, -1);
+                    String value = (col <= parts.length) ? parts[col - 1] : "";
+                    values.add(value);
+                    if (values.size() >= max) {
+                        break;
+                    }
+                }
+            }
+            StringBuilder sb = new StringBuilder();
+            sb.append("{\"ok\":true,\"col\":").append(col).append(",\"values\":[");
+            for (int i = 0; i < values.size(); i++) {
+                if (i > 0) {
+                    sb.append(",");
+                }
+                sb.append("\"").append(jsonEscape(values.get(i))).append("\"");
+            }
+            sb.append("]}");
+            sendJson(exchange, 200, sb.toString());
+        }
+    }
+
     private String buildStatusJson() {
         int stopRequested = owner.getSyncStopRequested();
         StringBuilder sb = new StringBuilder();

src/main/java/com/elphel/imagej/tileprocessor/QuadCLTCPU.java

@@ -257,10 +257,16 @@ public class QuadCLTCPU {
     public CorrectionFPN correctionFPN =      null;
     
     public GroundPlane ground_plane =         null;
-    
+    /*
     public HashSet<String> getRefScenes(){
     	return ref_scenes;
     }
+    */
+    public String [] getRefScenes() { // increasing timestamps
+    	String [] names = ref_scenes.toArray(new String[0]);
+    	Arrays.sort(names);
+    	return names;
+    }
     
     public void resetRefScenes() {
     	ref_scenes = null;
@@ -823,7 +829,7 @@ public class QuadCLTCPU {
     		CLTParameters clt_parameters,
         	int           quat_lma_mode,
         	double        avg_height,
-        	double        translation_weight,
+        	double        translation_weight,  // 1.0 - pure translation, 0.0 - pure rotation
     		QuadCLT[]     quadCLTs,
     		double [][][] xyzatr,
     		double [][][] ims_xyzatr,
@@ -1903,13 +1909,34 @@ public class QuadCLTCPU {
     		}
     	}
     	return fl;
-    	//    	if ((fl[0] >= 0) && (fl[1] >= 0)) {
-    	//    		return fl;
-    	//    	} else {
-    	//    		return null;
-    	//    	}
     }
 
+    public int [] getFirstLastIndex(String [] scene_names) { // should be ordered accending ts
+    	int [] fl = null;
+    	if ((timestamp_first != null) && (timestamp_last != null)) {
+    		fl = new int [] {-1,-1};
+    		if (scene_names != null) {
+    			int i = 0;
+    			for (; i < scene_names.length; i++) if (scene_names[i] != null) {
+    				if (timestamp_first.equals(scene_names[i])) {
+    					fl[0] = i;
+    					break;
+    				}
+    			}
+    			for (; i < scene_names.length; i++) if (scene_names[i] != null) {
+    				if (timestamp_last.equals(scene_names[i])) {
+    					fl[1] = i;
+    					break;
+    				}
+    			}
+    		}
+    	}
+    	return fl;
+    }
+    
+    
+    
+    
     /**
      * Set reference scene pointer by a reference scene timestamp.
      * @param ts reference scene pointer as String
@@ -1935,6 +1962,9 @@ public class QuadCLTCPU {
     	timestamp_first = ts0;
     	timestamp_last = ts1;
     }
+    public String[] getFirstLastTimestamps() {
+    	return new String [] {timestamp_first,timestamp_last};
+    }
 
     /**
      * Set first, last scene pointers by instances.